Drop [LegacyInterfaceTypeChecking] where trivial in Web Audio

third_party/WebKit/LayoutTests/webaudio/resources/audio-testing.js

Index: third_party/WebKit/LayoutTests/webaudio/resources/audio-testing.js
diff --git a/third_party/WebKit/LayoutTests/webaudio/resources/audio-testing.js b/third_party/WebKit/LayoutTests/webaudio/resources/audio-testing.js
index a838881c5a688d4502fc8b06e90e07e4cc498399..d48f7e8c8a4ef24e024ac7264a90c2635ced5d31 100644
--- a/third_party/WebKit/LayoutTests/webaudio/resources/audio-testing.js
+++ b/third_party/WebKit/LayoutTests/webaudio/resources/audio-testing.js
@@ -597,6 +597,8 @@ var Should = (function () {
                 this._testPassed('threw an exception of type ' + error.name);
             else if (error.name === errorType)
                 this._testPassed('threw ' + errorType + ': ' + error.message);
+            else if (self.hasOwnProperty(errorType) && error instanceof self[errorType])
+                this._testPassed('threw ' + errorType + ': ' + error.message);
             else
                 this._testFailed('threw ' + error.name + ' instead of ' + exception);
         }