--- a/configure.in
+++ b/configure.in
@@ -4136,30 +4136,28 @@ dnl = Enable the toolkit as needed      
 dnl ========================================================
 
 MOZ_WIDGET_GTK=
 
 case "$MOZ_WIDGET_TOOLKIT" in
 
 cairo-windows)
     MOZ_WIDGET_TOOLKIT=windows
-    MOZ_WEBGL=1
     MOZ_PDF_PRINTING=1
     MOZ_INSTRUMENT_EVENT_LOOP=1
     if test -n "$GNU_CC"; then
         MOZ_FOLD_LIBS=
     fi
     ;;
 
 cairo-gtk3)
     MOZ_WIDGET_TOOLKIT=gtk3
     MOZ_ENABLE_GTK=1
     MOZ_ENABLE_GTK3=1
     MOZ_ENABLE_XREMOTE=1
-    MOZ_WEBGL=1
     MOZ_GL_DEFAULT_PROVIDER=GLX
 
     AC_DEFINE(MOZ_X11)
     MOZ_X11=1
     USE_FC_FREETYPE=1
 
     TK_CFLAGS='$(MOZ_GTK3_CFLAGS)'
     TK_LIBS='$(MOZ_GTK3_LIBS)'
@@ -4169,17 +4167,16 @@ cairo-gtk3)
     MOZ_INSTRUMENT_EVENT_LOOP=1
     ;;
 
 cairo-gtk2|cairo-gtk2-x11)
     MOZ_WIDGET_TOOLKIT=gtk2
     MOZ_ENABLE_GTK=1
     MOZ_ENABLE_GTK2=1
     MOZ_ENABLE_XREMOTE=1
-    MOZ_WEBGL=1
     MOZ_GL_DEFAULT_PROVIDER=GLX
 
     AC_DEFINE(MOZ_X11)
     MOZ_X11=1
     USE_FC_FREETYPE=1
 
     TK_CFLAGS='$(MOZ_GTK2_CFLAGS)'
     TK_LIBS='$(MOZ_GTK2_LIBS)'
@@ -4196,17 +4193,16 @@ cairo-qt)
     if test -z "$WITHOUT_X11"; then
       MOZ_ENABLE_XREMOTE=1
       MOZ_GL_DEFAULT_PROVIDER=GLX
       MOZ_X11=1
       AC_DEFINE(MOZ_X11)
       XT_LIBS=
     fi
 
-    MOZ_WEBGL=1
     USE_FC_FREETYPE=1
     TK_CFLAGS='$(MOZ_QT_CFLAGS)'
     TK_LIBS='$(MOZ_QT_LIBS)'
     AC_DEFINE(MOZ_WIDGET_QT)
     MOZ_PDF_PRINTING=1
     AC_DEFINE(QT_NO_KEYWORDS)
     ;;
 
@@ -4217,17 +4213,16 @@ cairo-cocoa)
     # Use -Wl as a trick to avoid -framework and framework names from
     # being separated by AC_SUBST_LIST.
     TK_LIBS='-Wl,-framework,CoreLocation -Wl,-framework,QuartzCore -Wl,-framework,Carbon -Wl,-framework,CoreAudio -Wl,-framework,AudioToolbox -Wl,-framework,AudioUnit -Wl,-framework,AddressBook -Wl,-framework,OpenGL'
     TK_CFLAGS="-DNO_X11"
     CFLAGS="$CFLAGS $TK_CFLAGS"
     CXXFLAGS="$CXXFLAGS $TK_CFLAGS"
     MOZ_USER_DIR="Mozilla"
     MOZ_FS_LAYOUT=bundle
-    MOZ_WEBGL=1
     MOZ_INSTRUMENT_EVENT_LOOP=1
     ;;
 
 cairo-uikit)
     MOZ_WIDGET_TOOLKIT=uikit
     AC_DEFINE(MOZ_WIDGET_UIKIT)
     LDFLAGS="$LDFLAGS -framework UIKit -lobjc"
     TK_CFLAGS="-DNO_X11"
@@ -4238,28 +4233,26 @@ cairo-uikit)
     MOZ_FS_LAYOUT=bundle
     ;;
 
 cairo-android)
     AC_DEFINE(MOZ_WIDGET_ANDROID)
     MOZ_WIDGET_TOOLKIT=android
     TK_CFLAGS='$(MOZ_CAIRO_CFLAGS) $(MOZ_PIXMAN_CFLAGS)'
     TK_LIBS='$(MOZ_CAIRO_LIBS) $(MOZ_PIXMAN_LIBS)'
-    MOZ_WEBGL=1
     MOZ_PDF_PRINTING=1
     MOZ_INSTRUMENT_EVENT_LOOP=1
     ;;
 
 cairo-gonk)
     AC_DEFINE(MOZ_WIDGET_GONK)
     AC_DEFINE(MOZ_TOUCH)
     MOZ_WIDGET_TOOLKIT=gonk
     TK_CFLAGS='$(MOZ_CAIRO_CFLAGS) $(MOZ_PIXMAN_CFLAGS)'
     TK_LIBS='$(MOZ_CAIRO_LIBS) $(MOZ_PIXMAN_LIBS)'
-    MOZ_WEBGL=1
     MOZ_PDF_PRINTING=1
     MOZ_TOUCH=1
     MOZ_INSTRUMENT_EVENT_LOOP=1
     ;;
 
 esac
 
 AC_SUBST(MOZ_PDF_PRINTING)
@@ -5667,35 +5660,24 @@ case "${target_cpu}" in
 i*86)
   MOZ_D3D_CPU_SUFFIX=x86
   ;;
 x86_64)
   MOZ_D3D_CPU_SUFFIX=x64
   ;;
 esac
 
-MOZ_ARG_DISABLE_BOOL(webgl,
-[  --disable-webgl     Disable building of the WebGL implementation],
-    MOZ_WEBGL_DISABLED=1,
-    MOZ_WEBGL_DISABLED=)
-
 MOZ_ARG_ENABLE_BOOL(require-all-d3dc-versions,
 [  --enable-require-all-d3dc-versions Require all versions of the D3D compiler needed for supported Windows systems.],
     MOZ_REQUIRE_ALL_D3DCS=1,
     MOZ_REQUIRE_ALL_D3DCS=)
 
-if test -n "$MOZ_WEBGL_DISABLED"; then
-  MOZ_WEBGL=
-  MOZ_ANGLE_RENDERER=
-fi
-
-if test -n "$MOZ_WEBGL"; then
-  AC_DEFINE(MOZ_WEBGL)
-fi
-
+# This is potentially set in external mozconfig files; if it's set,
+# then the build exposes the "webgl" context name, which is reserved
+# for conformant implementations.
 if test -n "$MOZ_WEBGL_CONFORMANT"; then
   AC_DEFINE(MOZ_WEBGL_CONFORMANT)
 fi
 
 dnl ========================================================
 dnl D3D compiler DLL
 dnl ========================================================
 MOZ_FOUND_D3D_COMPILERS=
@@ -8387,17 +8369,16 @@ AC_SUBST(MOZ_CALLGRIND)
 AC_SUBST(MOZ_VTUNE)
 AC_SUBST(MOZ_PROFILING)
 AC_SUBST(LIBICONV)
 AC_SUBST(MOZ_PLACES)
 AC_SUBST(MOZ_SOCIAL)
 AC_SUBST(MOZ_TOOLKIT_SEARCH)
 AC_SUBST(MOZ_FEEDS)
 AC_SUBST(NS_PRINTING)
-AC_SUBST(MOZ_WEBGL)
 AC_SUBST(MOZ_HELP_VIEWER)
 AC_SUBST(TOOLCHAIN_PREFIX)
 
 AC_SUBST(JAVA)
 AC_SUBST(JAVAC)
 AC_SUBST(JAVAH)
 AC_SUBST(JAR)
 AC_SUBST(JARSIGNER)

--- a/content/html/content/src/HTMLCanvasElement.cpp
+++ b/content/html/content/src/HTMLCanvasElement.cpp
@@ -30,20 +30,17 @@
 #include "nsIWritablePropertyBag2.h"
 #include "nsIXPConnect.h"
 #include "nsJSUtils.h"
 #include "nsLayoutUtils.h"
 #include "nsMathUtils.h"
 #include "nsNetUtil.h"
 #include "nsStreamUtils.h"
 #include "ActiveLayerTracker.h"
-
-#ifdef MOZ_WEBGL
 #include "WebGL2Context.h"
-#endif
 
 using namespace mozilla::layers;
 using namespace mozilla::gfx;
 
 NS_IMPL_NS_NEW_HTML_ELEMENT(Canvas)
 
 namespace {
 
@@ -631,32 +628,31 @@ HTMLCanvasElement::GetContextHelper(cons
     Telemetry::Accumulate(Telemetry::CANVAS_2D_USED, 1);
     nsRefPtr<CanvasRenderingContext2D> ctx =
       new CanvasRenderingContext2D();
 
     ctx->SetCanvasElement(this);
     ctx.forget(aContext);
     return NS_OK;
   }
-#ifdef MOZ_WEBGL
+
   if (WebGL2Context::IsSupported() &&
       aContextId.EqualsLiteral("experimental-webgl2"))
   {
     Telemetry::Accumulate(Telemetry::CANVAS_WEBGL_USED, 1);
     nsRefPtr<WebGL2Context> ctx = WebGL2Context::Create();
 
     if (ctx == nullptr) {
       return NS_ERROR_NOT_IMPLEMENTED;
     }
 
     ctx->SetCanvasElement(this);
     ctx.forget(aContext);
     return NS_OK;
   }
-#endif
 
   NS_ConvertUTF16toUTF8 ctxId(aContextId);
 
   // check that ctxId is clamped to A-Za-z0-9_-
   for (uint32_t i = 0; i < ctxId.Length(); i++) {
     if ((ctxId[i] < 'A' || ctxId[i] > 'Z') &&
         (ctxId[i] < 'a' || ctxId[i] > 'z') &&
         (ctxId[i] < '0' || ctxId[i] > '9') &&

--- a/dom/canvas/moz.build
+++ b/dom/canvas/moz.build
@@ -20,96 +20,93 @@ EXPORTS.mozilla.dom += [
     'CanvasGradient.h',
     'CanvasPattern.h',
     'CanvasRenderingContext2D.h',
     'CanvasUtils.h',
     'ImageData.h',
     'TextMetrics.h',
 ]
 
+# Canvas 2D and common sources
 UNIFIED_SOURCES += [
     'CanvasImageCache.cpp',
     'CanvasRenderingContext2D.cpp',
     'CanvasUtils.cpp',
     'DocumentRendererChild.cpp',
     'DocumentRendererParent.cpp',
     'ImageData.cpp',
     'ImageEncoder.cpp',
 ]
 
-if CONFIG['MOZ_WEBGL']:
-    UNIFIED_SOURCES += [
-        'MurmurHash3.cpp',
-        'WebGL1Context.cpp',
-        'WebGL2Context.cpp',
-        'WebGLActiveInfo.cpp',
-        'WebGLBindableName.cpp',
-        'WebGLBuffer.cpp',
-        'WebGLContext.cpp',
-        'WebGLContextAsyncQueries.cpp',
-        'WebGLContextBuffers.cpp',
-        'WebGLContextDraw.cpp',
-        'WebGLContextExtensions.cpp',
-        'WebGLContextFramebufferOperations.cpp',
-        'WebGLContextGL.cpp',
-        'WebGLContextLossTimer.cpp',
-        'WebGLContextReporter.cpp',
-        'WebGLContextState.cpp',
-        'WebGLContextUtils.cpp',
-        'WebGLContextValidate.cpp',
-        'WebGLContextVertexArray.cpp',
-        'WebGLContextVertices.cpp',
-        'WebGLElementArrayCache.cpp',
-        'WebGLExtensionBase.cpp',
-        'WebGLExtensionBlendMinMax.cpp',
-        'WebGLExtensionColorBufferFloat.cpp',
-        'WebGLExtensionColorBufferHalfFloat.cpp',
-        'WebGLExtensionCompressedTextureATC.cpp',
-        'WebGLExtensionCompressedTextureETC1.cpp',
-        'WebGLExtensionCompressedTexturePVRTC.cpp',
-        'WebGLExtensionCompressedTextureS3TC.cpp',
-        'WebGLExtensionDebugRendererInfo.cpp',
-        'WebGLExtensionDebugShaders.cpp',
-        'WebGLExtensionDepthTexture.cpp',
-        'WebGLExtensionDrawBuffers.cpp',
-        'WebGLExtensionElementIndexUint.cpp',
-        'WebGLExtensionFragDepth.cpp',
-        'WebGLExtensionInstancedArrays.cpp',
-        'WebGLExtensionLoseContext.cpp',
-        'WebGLExtensionShaderTextureLod.cpp',
-        'WebGLExtensionSRGB.cpp',
-        'WebGLExtensionStandardDerivatives.cpp',
-        'WebGLExtensionTextureFilterAnisotropic.cpp',
-        'WebGLExtensionTextureFloat.cpp',
-        'WebGLExtensionTextureFloatLinear.cpp',
-        'WebGLExtensionTextureHalfFloat.cpp',
-        'WebGLExtensionTextureHalfFloatLinear.cpp',
-        'WebGLExtensionVertexArray.cpp',
-        'WebGLFramebuffer.cpp',
-        'WebGLFramebufferAttachable.cpp',
-        'WebGLObjectModel.cpp',
-        'WebGLProgram.cpp',
-        'WebGLQuery.cpp',
-        'WebGLRenderbuffer.cpp',
-        'WebGLShader.cpp',
-        'WebGLShaderPrecisionFormat.cpp',
-        'WebGLTexelConversions.cpp',
-        'WebGLTexture.cpp',
-        'WebGLUniformLocation.cpp',
-        'WebGLVertexArray.cpp',
-        'WebGLVertexArrayFake.cpp',
-        'WebGLVertexArrayGL.cpp',
-    ]
-    LOCAL_INCLUDES += [
-        '/js/xpconnect/wrappers',
-    ]
-else:
-    UNIFIED_SOURCES += [
-        'WebGLContextNotSupported.cpp',
-    ]
+# WebGL Sources
+UNIFIED_SOURCES += [
+    'MurmurHash3.cpp',
+    'WebGL1Context.cpp',
+    'WebGL2Context.cpp',
+    'WebGLActiveInfo.cpp',
+    'WebGLBindableName.cpp',
+    'WebGLBuffer.cpp',
+    'WebGLContext.cpp',
+    'WebGLContextAsyncQueries.cpp',
+    'WebGLContextBuffers.cpp',
+    'WebGLContextDraw.cpp',
+    'WebGLContextExtensions.cpp',
+    'WebGLContextFramebufferOperations.cpp',
+    'WebGLContextGL.cpp',
+    'WebGLContextLossTimer.cpp',
+    'WebGLContextReporter.cpp',
+    'WebGLContextState.cpp',
+    'WebGLContextUtils.cpp',
+    'WebGLContextValidate.cpp',
+    'WebGLContextVertexArray.cpp',
+    'WebGLContextVertices.cpp',
+    'WebGLElementArrayCache.cpp',
+    'WebGLExtensionBase.cpp',
+    'WebGLExtensionBlendMinMax.cpp',
+    'WebGLExtensionColorBufferFloat.cpp',
+    'WebGLExtensionColorBufferHalfFloat.cpp',
+    'WebGLExtensionCompressedTextureATC.cpp',
+    'WebGLExtensionCompressedTextureETC1.cpp',
+    'WebGLExtensionCompressedTexturePVRTC.cpp',
+    'WebGLExtensionCompressedTextureS3TC.cpp',
+    'WebGLExtensionDebugRendererInfo.cpp',
+    'WebGLExtensionDebugShaders.cpp',
+    'WebGLExtensionDepthTexture.cpp',
+    'WebGLExtensionDrawBuffers.cpp',
+    'WebGLExtensionElementIndexUint.cpp',
+    'WebGLExtensionFragDepth.cpp',
+    'WebGLExtensionInstancedArrays.cpp',
+    'WebGLExtensionLoseContext.cpp',
+    'WebGLExtensionShaderTextureLod.cpp',
+    'WebGLExtensionSRGB.cpp',
+    'WebGLExtensionStandardDerivatives.cpp',
+    'WebGLExtensionTextureFilterAnisotropic.cpp',
+    'WebGLExtensionTextureFloat.cpp',
+    'WebGLExtensionTextureFloatLinear.cpp',
+    'WebGLExtensionTextureHalfFloat.cpp',
+    'WebGLExtensionTextureHalfFloatLinear.cpp',
+    'WebGLExtensionVertexArray.cpp',
+    'WebGLFramebuffer.cpp',
+    'WebGLFramebufferAttachable.cpp',
+    'WebGLObjectModel.cpp',
+    'WebGLProgram.cpp',
+    'WebGLQuery.cpp',
+    'WebGLRenderbuffer.cpp',
+    'WebGLShader.cpp',
+    'WebGLShaderPrecisionFormat.cpp',
+    'WebGLTexelConversions.cpp',
+    'WebGLTexture.cpp',
+    'WebGLUniformLocation.cpp',
+    'WebGLVertexArray.cpp',
+    'WebGLVertexArrayFake.cpp',
+    'WebGLVertexArrayGL.cpp',
+]
+LOCAL_INCLUDES += [
+    '/js/xpconnect/wrappers',
+]
 
 FAIL_ON_WARNINGS = True
 
 MSVC_ENABLE_PGO = True
 
 include('/ipc/chromium/chromium-config.mozbuild')
 
 FINAL_LIBRARY = 'xul'

--- a/dom/webidl/moz.build
+++ b/dom/webidl/moz.build
@@ -473,16 +473,18 @@ WEBIDL_FILES = [
     'VideoPlaybackQuality.webidl',
     'VideoStreamTrack.webidl',
     'VideoTrack.webidl',
     'VideoTrackList.webidl',
     'VTTCue.webidl',
     'VTTRegion.webidl',
     'WaveShaperNode.webidl',
     'WebComponents.webidl',
+    'WebGL2RenderingContext.webidl',
+    'WebGLRenderingContext.webidl',
     'WebSocket.webidl',
     'WheelEvent.webidl',
     'WifiOptions.webidl',
     'Worker.webidl',
     'WorkerGlobalScope.webidl',
     'WorkerLocation.webidl',
     'WorkerNavigator.webidl',
     'XMLDocument.webidl',
@@ -499,22 +501,16 @@ WEBIDL_FILES = [
     'XULElement.webidl',
 ]
 
 if CONFIG['MOZ_AUDIO_CHANNEL_MANAGER']:
     WEBIDL_FILES += [
         'AudioChannelManager.webidl',
     ]
 
-if CONFIG['MOZ_WEBGL']:
-    WEBIDL_FILES += [
-        'WebGL2RenderingContext.webidl',
-        'WebGLRenderingContext.webidl',
-    ]
-
 if CONFIG['MOZ_WEBRTC']:
     WEBIDL_FILES += [
         'DataChannel.webidl',
         'MediaStreamList.webidl',
         'PeerConnectionImpl.webidl',
         'PeerConnectionImplEnums.webidl',
         'PeerConnectionObserver.webidl',
         'PeerConnectionObserverEnums.webidl',

--- a/gfx/gl/GLLibraryEGL.cpp
+++ b/gfx/gl/GLLibraryEGL.cpp
@@ -109,17 +109,16 @@ GLLibraryEGL::EnsureInitialized()
     mozilla::ScopedGfxFeatureReporter reporter("EGL");
 
 #ifdef MOZ_B2G
     if (!sCurrentContext.init())
 	    MOZ_CRASH("Tls init failed");
 #endif
 
 #ifdef XP_WIN
-#ifdef MOZ_WEBGL
     if (!mEGLLibrary) {
         // On Windows, the GLESv2, EGL and DXSDK libraries are shipped with libxul and
         // we should look for them there. We have to load the libs in this
         // order, because libEGL.dll depends on libGLESv2.dll which depends on the DXSDK
         // libraries. This matters especially for WebRT apps which are in a different directory.
         // See bug 760323 and bug 749459
 
         // Also note that we intentionally leak the libs we load.
@@ -148,17 +147,17 @@ GLLibraryEGL::EnsureInitialized()
 
         LoadLibraryForEGLOnWindows(NS_LITERAL_STRING("libGLESv2.dll"));
 
         mEGLLibrary = LoadLibraryForEGLOnWindows(NS_LITERAL_STRING("libEGL.dll"));
 
         if (!mEGLLibrary)
             return false;
     }
-#endif // MOZ_WEBGL
+
 #else // !Windows
 
     // On non-Windows (Android) we use system copies of libEGL. We look for
     // the APITrace lib, libEGL.so, and libEGL.so.1 in that order.
 
 #if defined(ANDROID)
     if (!mEGLLibrary)
         mEGLLibrary = LoadApitraceLibrary();