Fix BaseAudioContext::hasPendingActivity() to make it GCed correctly

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 5cbe92c150b07aa9938853951645f4b81ed64729..12479de0a57b597b77159a3e9a64dda3a09b0611 100644
--- a/third_party/WebKit/LayoutTests/webaudio/resources/audio-testing.js
+++ b/third_party/WebKit/LayoutTests/webaudio/resources/audio-testing.js
@@ -597,6 +597,20 @@ var Should = (function () {
         throw failureMessage;
     };
 
+    // Check if |target| does exist. (not undefined nor null)
+    //
+    // Example:
+    // Should('null', null).exist();
+    // Result:
+    // "FAIL null does not exist."
+    ShouldModel.prototype.exist = function () {
+        if (this.target !== null && this.target !== undefined) {
+            this._testPassed('exist');
+        } else {
+            this._testFailed('does not exist');
+        }
+    };
+
     // Check if |target| is equal to |value|.
     //
     // Example: