Bug 1614019 - Removed negative value from the valid range r=padenot,webidl,smaug

The condition in the if is changed because the minus operation could overflow.
The declaration of sampleRate has been moved to its next use because its first value was never used.

Differential Revision: https://phabricator.services.mozilla.com/D81550

dom/media/webaudio/AudioContext.cpp

@@ -261,17 +261,18 @@ already_AddRefed<AudioContext> AudioContext::Constructor(
     aRv.Throw(NS_ERROR_FAILURE);
     return nullptr;
   }
-
-  float sampleRate = MediaTrackGraph::REQUEST_DEFAULT_SAMPLE_RATE;
-  if (aOptions.mSampleRate > 0 &&
-      (aOptions.mSampleRate - WebAudioUtils::MinSampleRate < 0.0 ||
-       WebAudioUtils::MaxSampleRate - aOptions.mSampleRate < 0.0)) {
+  if (aOptions.mSampleRate.WasPassed() &&
+      (aOptions.mSampleRate.Value() < WebAudioUtils::MinSampleRate ||
+       aOptions.mSampleRate.Value() > WebAudioUtils::MaxSampleRate)) {
     aRv.ThrowNotSupportedError(nsPrintfCString(
-        "Sample rate %g is not in the range [%u, %u]", aOptions.mSampleRate,
-        WebAudioUtils::MinSampleRate, WebAudioUtils::MaxSampleRate));
+        "Sample rate %g is not in the range [%u, %u]",
+        aOptions.mSampleRate.Value(), WebAudioUtils::MinSampleRate,
+        WebAudioUtils::MaxSampleRate));
     return nullptr;
   }
-  sampleRate = aOptions.mSampleRate;
+  float sampleRate = aOptions.mSampleRate.WasPassed()
+                         ? aOptions.mSampleRate.Value()
+                         : MediaTrackGraph::REQUEST_DEFAULT_SAMPLE_RATE;
 
   RefPtr<AudioContext> object =
       new AudioContext(window, false, 2, 0, sampleRate);

dom/webidl/AudioContext.webidl

@@ -11,7 +11,7 @@
  */
 
 dictionary AudioContextOptions {
-             float        sampleRate = 0;
+             float        sampleRate;
 };
 
 dictionary AudioTimestamp {