Added tests to previously broken functionality and added null checks.

sdk/lib/web_audio/dartium/web_audio_dartium.dart

Index: sdk/lib/web_audio/dartium/web_audio_dartium.dart
diff --git a/sdk/lib/web_audio/dartium/web_audio_dartium.dart b/sdk/lib/web_audio/dartium/web_audio_dartium.dart
index d71875ca41f14b59081b21e0a726c90a2d78f6ec..260cb0715366750f9da014cc43973f78d77502b3 100644
--- a/sdk/lib/web_audio/dartium/web_audio_dartium.dart
+++ b/sdk/lib/web_audio/dartium/web_audio_dartium.dart
@@ -196,15 +196,15 @@ class AudioBufferSourceNode extends AudioSourceNode {
   int get playbackState native "AudioBufferSourceNode_playbackState_Getter";
 
   void start(num when, [num grainOffset, num grainDuration]) {
-    if ((when is num || when == null) && !?grainOffset && !?grainDuration) {
+    if (when is num && !?grainOffset && !?grainDuration) {

[blois, 2013/05/13 21:09:16]

when is when not a num?

       _start_1(when);
       return;
     }
-    if ((when is num || when == null) && (grainOffset is num || grainOffset == null) && !?grainDuration) {
+    if (grainOffset is num && grainOffset != null && when is num && !?grainDuration) {
       _start_2(when, grainOffset);
       return;
     }
-    if ((when is num || when == null) && (grainOffset is num || grainOffset == null) && (grainDuration is num || grainDuration == null)) {
+    if (grainDuration is num && grainDuration != null && grainOffset is num && grainOffset != null && when is num) {
       _start_3(when, grainOffset, grainDuration);
       return;
     }
@@ -271,10 +271,10 @@ class AudioContext extends EventTarget {
   BiquadFilterNode createBiquadFilter() native "AudioContext_createBiquadFilter_Callback";
 
   AudioBuffer createBuffer(buffer_OR_numberOfChannels, mixToMono_OR_numberOfFrames, [num sampleRate]) {
-    if ((buffer_OR_numberOfChannels is int || buffer_OR_numberOfChannels == null) && (mixToMono_OR_numberOfFrames is int || mixToMono_OR_numberOfFrames == null) && (sampleRate is num || sampleRate == null)) {
+    if (sampleRate is num && sampleRate != null && mixToMono_OR_numberOfFrames is int && mixToMono_OR_numberOfFrames != null && buffer_OR_numberOfChannels is int && buffer_OR_numberOfChannels != null) {
       return _createBuffer_1(buffer_OR_numberOfChannels, mixToMono_OR_numberOfFrames, sampleRate);
     }
-    if ((buffer_OR_numberOfChannels is ByteBuffer || buffer_OR_numberOfChannels == null) && (mixToMono_OR_numberOfFrames is bool || mixToMono_OR_numberOfFrames == null) && !?sampleRate) {
+    if (mixToMono_OR_numberOfFrames is bool && mixToMono_OR_numberOfFrames != null && buffer_OR_numberOfChannels is ByteBuffer && buffer_OR_numberOfChannels != null && !?sampleRate) {
       return _createBuffer_2(buffer_OR_numberOfChannels, mixToMono_OR_numberOfFrames);
     }
     throw new ArgumentError("Incorrect number or type of arguments");
@@ -497,11 +497,11 @@ class AudioNode extends NativeFieldWrapperClass1 {
   int get numberOfOutputs native "AudioNode_numberOfOutputs_Getter";
 
   void connect(destination, int output, [int input]) {
-    if ((destination is AudioNode || destination == null) && (output is int || output == null) && (input is int || input == null)) {
+    if (input is int && input != null && output is int && destination is AudioNode && destination != null) {
       _connect_1(destination, output, input);
       return;
     }
-    if ((destination is AudioParam || destination == null) && (output is int || output == null) && !?input) {
+    if (output is int && destination is AudioParam && destination != null && !?input) {
       _connect_2(destination, output);
       return;
     }