Fix bug in audiobuffersource-duration-loop test

The test was producing a failure that the array lengths didn't match.
(Not sure why the test was marked as passing even though it failed.)
The problem was that we actually had audioBuffer.getChannelData
instead of audioBuffer.getChannelData(0) to get the data from the
first channel.

Correct the mistake and also run clang-format over the code to clean
it up.

Bug: 1217791
Change-Id: I510838337e2948b89fb0622b63dd81e022d103d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2945641
Reviewed-by: Hongchan Choi <hongchan@chromium.org>
Commit-Queue: Raymond Toy <rtoy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#891341}

Author: Raymond Toy

webaudio/the-audio-api/the-audiobuffersourcenode-interface/audiobuffersource-duration-loop.html

@@ -18,7 +18,7 @@
 
         // Create the sample buffer and fill the second half with 1
         let buffer = context.createBuffer(1, 2048, context.sampleRate);
-        for(let i = 1024; i < 2048; i++) {
+        for (let i = 1024; i < 2048; i++) {
           buffer.getChannelData(0)[i] = 1;
         }
 
@@ -32,15 +32,17 @@
         source.start(0, 1024 / context.sampleRate, 2048 / context.sampleRate);
         // Expectations
         let expected = new Float32Array(4096);
-        for(let i = 0; i < 2048; i++) {
+        for (let i = 0; i < 2048; i++) {
           expected[i] = 1;
         }
         // Render it!
         context.startRendering()
-          .then(function(audioBuffer) {
-            should(audioBuffer.getChannelData, "audioBuffer.getChannelData").beEqualToArray(expected);
-          })
-          .then(task.done());
+            .then(function(audioBuffer) {
+              should(
+                  audioBuffer.getChannelData(0), 'audioBuffer.getChannelData')
+                  .beEqualToArray(expected);
+            })
+            .then(task.done());
       });
 
       audit.run();