--- a/dom/canvas/WebGLContext.cpp
+++ b/dom/canvas/WebGLContext.cpp
@@ -1363,16 +1363,17 @@ WebGLContext::ForceClearFramebufferWithD
 {
     MakeContextCurrent();
 
     bool initializeColorBuffer = 0 != (mask & LOCAL_GL_COLOR_BUFFER_BIT);
     bool initializeDepthBuffer = 0 != (mask & LOCAL_GL_DEPTH_BUFFER_BIT);
     bool initializeStencilBuffer = 0 != (mask & LOCAL_GL_STENCIL_BUFFER_BIT);
     bool drawBuffersIsEnabled = IsExtensionEnabled(WebGLExtensionID::WEBGL_draw_buffers);
     bool shouldOverrideDrawBuffers = false;
+    bool usingDefaultFrameBuffer = !mBoundDrawFramebuffer;
 
     GLenum currentDrawBuffers[WebGLContext::kMaxColorAttachments];
 
     // Fun GL fact: No need to worry about the viewport here, glViewport is just
     // setting up a coordinates transformation, it doesn't affect glClear at all.
     AssertCachedState(); // Can't check cached bindings, as we could
                          // have a different FB bound temporarily.
 
@@ -1380,27 +1381,37 @@ WebGLContext::ForceClearFramebufferWithD
     gl->fDisable(LOCAL_GL_SCISSOR_TEST);
 
     if (initializeColorBuffer) {
 
         if (drawBuffersIsEnabled) {
 
             GLenum drawBuffersCommand[WebGLContext::kMaxColorAttachments] = { LOCAL_GL_NONE };
 
-            for(int32_t i = 0; i < mGLMaxDrawBuffers; i++) {
+            for (int32_t i = 0; i < mGLMaxDrawBuffers; i++) {
                 GLint temp;
                 gl->fGetIntegerv(LOCAL_GL_DRAW_BUFFER0 + i, &temp);
                 currentDrawBuffers[i] = temp;
 
                 if (colorAttachmentsMask[i]) {
                     drawBuffersCommand[i] = LOCAL_GL_COLOR_ATTACHMENT0 + i;
                 }
                 if (currentDrawBuffers[i] != drawBuffersCommand[i])
                     shouldOverrideDrawBuffers = true;
             }
+
+            // When clearing the default framebuffer, we must be clearing only
+            // GL_BACK, and nothing else, or else gl may return an error. We will
+            // only use the first element of currentDrawBuffers in this case.
+            if (usingDefaultFrameBuffer) {
+                gl->Screen()->SetDrawBuffer(LOCAL_GL_BACK);
+                if (currentDrawBuffers[0] == LOCAL_GL_COLOR_ATTACHMENT0)
+                    currentDrawBuffers[0] = LOCAL_GL_BACK;
+                shouldOverrideDrawBuffers = false;
+            }
             // calling draw buffers can cause resolves on adreno drivers so
             // we try to avoid calling it
             if (shouldOverrideDrawBuffers)
                 gl->fDrawBuffers(mGLMaxDrawBuffers, drawBuffersCommand);
         }
 
         gl->fColorMask(1, 1, 1, 1);
 
@@ -1436,18 +1447,23 @@ WebGLContext::ForceClearFramebufferWithD
         gl->fEnable(LOCAL_GL_SCISSOR_TEST);
 
     if (mRasterizerDiscardEnabled) {
         gl->fEnable(LOCAL_GL_RASTERIZER_DISCARD);
     }
 
     // Restore GL state after clearing.
     if (initializeColorBuffer) {
-        if (shouldOverrideDrawBuffers) {
-            gl->fDrawBuffers(mGLMaxDrawBuffers, currentDrawBuffers);
+
+        if (drawBuffersIsEnabled) {
+            if (usingDefaultFrameBuffer) {
+                gl->Screen()->SetDrawBuffer(currentDrawBuffers[0]);
+            } else if (shouldOverrideDrawBuffers) {
+                gl->fDrawBuffers(mGLMaxDrawBuffers, currentDrawBuffers);
+            }
         }
 
         gl->fColorMask(mColorWriteMask[0],
                        mColorWriteMask[1],
                        mColorWriteMask[2],
                        mColorWriteMask[3]);
         gl->fClearColor(mColorClearValue[0],
                         mColorClearValue[1],