--- a/dom/media/webaudio/AudioWorkletGlobalScope.cpp
+++ b/dom/media/webaudio/AudioWorkletGlobalScope.cpp
@@ -364,10 +364,14 @@ bool AudioWorkletGlobalScope::ConstructP
   if (NS_WARN_IF(!ToJSValue(cx, processor, &processorVal))) {
     return false;
   }
   MOZ_ASSERT(processorVal.isObject());
   aRetProcessor.set(&processorVal.toObject());
   return true;
 }
 
+RefPtr<MessagePort> AudioWorkletGlobalScope::TakePortForProcessorCtor() {
+  return std::move(mPortForProcessor);
+}
+
 }  // namespace dom
 }  // namespace mozilla

--- a/dom/media/webaudio/AudioWorkletGlobalScope.h
+++ b/dom/media/webaudio/AudioWorkletGlobalScope.h
@@ -49,16 +49,20 @@ class AudioWorkletGlobalScope final : pu
   // If successful, returns true and sets aRetProcessor, which will be in the
   // compartment for the realm of this global.  Returns false on failure.
   MOZ_CAN_RUN_SCRIPT
   bool ConstructProcessor(const nsAString& aName,
                           NotNull<StructuredCloneHolder*> aSerializedOptions,
                           UniqueMessagePortId& aPortIdentifier,
                           JS::MutableHandle<JSObject*> aRetProcessor);
 
+  // Returns null if not called during ConstructProcessor() or if the port has
+  // already been taken.
+  RefPtr<MessagePort> TakePortForProcessorCtor();
+
  private:
   ~AudioWorkletGlobalScope() = default;
 
   // Returns an AudioParamDescriptorMap filled with AudioParamDescriptor
   // objects, extracted from JS. Returns an empty map in case of error and set
   // aRv accordingly.
   AudioParamDescriptorMap DescriptorsFromJS(
       JSContext* aCx, const JS::Rooted<JS::Value>& aDescriptors,

--- a/dom/media/webaudio/AudioWorkletProcessor.cpp
+++ b/dom/media/webaudio/AudioWorkletProcessor.cpp
@@ -9,40 +9,45 @@
 #include "mozilla/dom/AudioWorkletNodeBinding.h"
 #include "mozilla/dom/AudioWorkletProcessorBinding.h"
 #include "mozilla/dom/MessagePort.h"
 #include "nsIGlobalObject.h"
 
 namespace mozilla {
 namespace dom {
 
-NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(AudioWorkletProcessor, mParent)
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(AudioWorkletProcessor, mParent, mPort)
 
 NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(AudioWorkletProcessor, AddRef)
 NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(AudioWorkletProcessor, Release)
 
-AudioWorkletProcessor::AudioWorkletProcessor(nsIGlobalObject* aParent)
-    : mParent(aParent) {}
+AudioWorkletProcessor::AudioWorkletProcessor(nsIGlobalObject* aParent,
+                                             MessagePort* aPort)
+    : mParent(aParent), mPort(aPort) {}
+
+AudioWorkletProcessor::~AudioWorkletProcessor() = default;
 
 /* static */
 already_AddRefed<AudioWorkletProcessor> AudioWorkletProcessor::Constructor(
-    const GlobalObject& aGlobal, const AudioWorkletNodeOptions& aOptions) {
-  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+    const GlobalObject& aGlobal, const AudioWorkletNodeOptions& aOptions,
+    ErrorResult& aRv) {
+  nsCOMPtr<WorkletGlobalScope> global =
+      do_QueryInterface(aGlobal.GetAsSupports());
   MOZ_ASSERT(global);
-
+  RefPtr<MessagePort> port = static_cast<AudioWorkletGlobalScope*>(global.get())
+                                 ->TakePortForProcessorCtor();
+  if (!port) {
+    aRv.ThrowTypeError<MSG_ILLEGAL_CONSTRUCTOR>();
+    return nullptr;
+  }
   RefPtr<AudioWorkletProcessor> audioWorkletProcessor =
-      new AudioWorkletProcessor(global);
+      new AudioWorkletProcessor(global, port);
 
   return audioWorkletProcessor.forget();
 }
 
 JSObject* AudioWorkletProcessor::WrapObject(JSContext* aCx,
                                             JS::Handle<JSObject*> aGivenProto) {
   return AudioWorkletProcessor_Binding::Wrap(aCx, this, aGivenProto);
 }
 
-MessagePort* AudioWorkletProcessor::GetPort(ErrorResult& aRv) const {
-  aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
-  return nullptr;
-}
-
 }  // namespace dom
 }  // namespace mozilla

--- a/dom/media/webaudio/AudioWorkletProcessor.h
+++ b/dom/media/webaudio/AudioWorkletProcessor.h
@@ -23,27 +23,29 @@ class GlobalObject;
 class MessagePort;
 
 class AudioWorkletProcessor final : public nsWrapperCache {
  public:
   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(AudioWorkletProcessor)
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(AudioWorkletProcessor)
 
   static already_AddRefed<AudioWorkletProcessor> Constructor(
-      const GlobalObject& aGlobal, const AudioWorkletNodeOptions& aOptions);
+      const GlobalObject& aGlobal, const AudioWorkletNodeOptions& aOptions,
+      ErrorResult& aRv);
 
   nsIGlobalObject* GetParentObject() const { return mParent; }
 
   JSObject* WrapObject(JSContext* aCx,
                        JS::Handle<JSObject*> aGivenProto) override;
 
-  MessagePort* GetPort(ErrorResult& aRv) const;
+  MessagePort* Port() const { return mPort; };
 
  private:
-  explicit AudioWorkletProcessor(nsIGlobalObject* aParent);
-  ~AudioWorkletProcessor() = default;
+  explicit AudioWorkletProcessor(nsIGlobalObject* aParent, MessagePort* aPort);
+  ~AudioWorkletProcessor();
   nsCOMPtr<nsIGlobalObject> mParent;
+  RefPtr<MessagePort> mPort;
 };
 
 }  // namespace dom
 }  // namespace mozilla
 
 #endif  // AudioWorkletProcessor_h_

--- a/dom/webidl/AudioWorkletProcessor.webidl
+++ b/dom/webidl/AudioWorkletProcessor.webidl
@@ -7,13 +7,13 @@
  * https://webaudio.github.io/web-audio-api/#audioworkletprocessor
  *
  * Copyright © 2018 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C
  * liability, trademark and document use rules apply.
  */
 
 [Exposed=AudioWorklet]
 interface AudioWorkletProcessor {
-    constructor(optional AudioWorkletNodeOptions options = {});
+  [Throws]
+  constructor(optional AudioWorkletNodeOptions options = {});
 
-    [Throws]
-    readonly attribute MessagePort port;
+  readonly attribute MessagePort port;
 };

--- a/testing/web-platform/meta/webaudio/the-audio-api/the-audioworklet-interface/audioworklet-messageport.https.html.ini
+++ b/testing/web-platform/meta/webaudio/the-audio-api/the-audioworklet-interface/audioworklet-messageport.https.html.ini
@@ -1,14 +1,12 @@
 [audioworklet-messageport.https.html]
   bug: AudioWorklet not enabled on release_or_beta
   expected:
     if release_or_beta: ERROR
-    TIMEOUT
   [Executing "Test postMessage from AudioWorkletProcessor to AudioWorkletNode"]
-    expected: TIMEOUT
+    expected:
+      if release_or_beta: FAIL
 
   [Executing "Test postMessage from AudioWorkletNode to AudioWorkletProcessor"]
-    expected: NOTRUN
+    expected:
+      if release_or_beta: FAIL
 
-  [Audit report]
-    expected: NOTRUN
-

--- a/testing/web-platform/meta/webaudio/the-audio-api/the-audioworklet-interface/audioworkletnode-output-channel-count.https.html.ini
+++ b/testing/web-platform/meta/webaudio/the-audio-api/the-audioworklet-interface/audioworkletnode-output-channel-count.https.html.ini
@@ -1,14 +1,13 @@
 [audioworkletnode-output-channel-count.https.html]
   bug: AudioWorklet not enabled on release_or_beta
   expected:
     if release_or_beta: ERROR
-    TIMEOUT
-  [Executing "Dynamically change the channel count to if unspecified."]
-    expected: TIMEOUT
+  [X The expected output channel count is not equal to 17. Got 1.]
+    expected: FAIL
 
-  [Executing "Givien outputChannelCount must be honored."]
-    expected: NOTRUN
+  [< [Dynamically change the channel count to if unspecified.\] 1 out of 1 assertions were failed.]
+    expected: FAIL
 
-  [Audit report]
-    expected: NOTRUN
+  [# AUDIT TASK RUNNER FINISHED: 1 out of 2 tasks were failed.]
+    expected: FAIL
 

--- a/testing/web-platform/meta/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-options.https.html.ini
+++ b/testing/web-platform/meta/webaudio/the-audio-api/the-audioworklet-interface/audioworkletprocessor-options.https.html.ini
@@ -1,20 +1,20 @@
 [audioworkletprocessor-options.https.html]
-  expected:
-    if release_or_beta: OK
-    TIMEOUT
   [Executing "valid-processor-data"]
     bug: AudioWorklet not enabled on release_or_beta
     expected:
       if release_or_beta: FAIL
-      TIMEOUT
 
   [Executing "empty-option"]
     bug: AudioWorklet not enabled on release_or_beta
     expected:
       if release_or_beta: FAIL
-      NOTRUN
+
+  [X Number of properties in data from processor is not equal to 2. Got 3.]
+    expected: FAIL
 
-  [Audit report]
-    expected:
-      if release_or_beta: PASS
-      NOTRUN
+  [< [empty-option\] 1 out of 3 assertions were failed.]
+    expected: FAIL
+
+  [# AUDIT TASK RUNNER FINISHED: 1 out of 2 tasks were failed.]
+    expected: FAIL
+

--- a/testing/web-platform/meta/webaudio/the-audio-api/the-channelmergernode-interface/active-processing.https.html.ini
+++ b/testing/web-platform/meta/webaudio/the-audio-api/the-channelmergernode-interface/active-processing.https.html.ini
@@ -1,19 +1,19 @@
 [active-processing.https.html]
-  expected:
-    if release_or_beta: OK
-    TIMEOUT
   [Executing "initialize"]
     bug: AudioWorklet not enabled on release_or_beta
     expected:
       if release_or_beta: FAIL
 
   [Executing "test"]
     expected:
       if release_or_beta: FAIL
-      TIMEOUT
+
+  [X Test 1: Number of convolver output channels is not equal to 1. Got 0.]
+    expected: FAIL
 
-  [Audit report]
-    expected:
-      if release_or_beta: PASS
-      NOTRUN
+  [< [test\] 1 out of 3 assertions were failed.]
+    expected: FAIL
 
+  [# AUDIT TASK RUNNER FINISHED: 1 out of 2 tasks were failed.]
+    expected: FAIL
+

--- a/testing/web-platform/meta/webaudio/the-audio-api/the-convolvernode-interface/active-processing.https.html.ini
+++ b/testing/web-platform/meta/webaudio/the-audio-api/the-convolvernode-interface/active-processing.https.html.ini
@@ -1,19 +1,19 @@
 [active-processing.https.html]
-  expected:
-    if release_or_beta: OK
-    TIMEOUT
   [Executing "initialize"]
     bug: AudioWorklet not enabled on release_or_beta
     expected:
       if release_or_beta: FAIL
 
   [Executing "test"]
     expected:
       if release_or_beta: FAIL
-      TIMEOUT
+
+  [X Number of distinct values is not equal to 2. Got 0.]
+    expected: FAIL
 
-  [Audit report]
-    expected:
-      if release_or_beta: PASS
-      NOTRUN
+  [# AUDIT TASK RUNNER FINISHED: 1 out of 2 tasks were failed.]
+    expected: FAIL
 
+  [< [test\] 1 out of 1 assertions were failed.]
+    expected: FAIL
+

--- a/testing/web-platform/meta/webaudio/the-audio-api/the-mediaelementaudiosourcenode-interface/cors-check.https.html.ini
+++ b/testing/web-platform/meta/webaudio/the-audio-api/the-mediaelementaudiosourcenode-interface/cors-check.https.html.ini
@@ -1,11 +1,22 @@
 [cors-check.https.html]
   bug: AudioWorklet not enabled on release_or_beta
   expected:
     if release_or_beta: ERROR
-    TIMEOUT
-  [Executing "start-playback-and-capture"]
-    expected: TIMEOUT
+  [X Recorded channel #0 should have contain at least one value different from 0.]
+    expected: FAIL
+
+  [X Recorded channel #3 should have contain at least one value different from 0.]
+    expected: FAIL
+
+  [< [start-playback-and-capture\] 4 out of 4 assertions were failed.]
+    expected: FAIL
 
-  [Audit report]
-    expected: NOTRUN
+  [# AUDIT TASK RUNNER FINISHED: 1 out of 2 tasks were failed.]
+    expected: FAIL
 
+  [X Recorded channel #2 should have contain at least one value different from 0.]
+    expected: FAIL
+
+  [X Recorded channel #1 should have contain at least one value different from 0.]
+    expected: FAIL
+