Fix for github issue 119

Make the nominal range for the `sampleRate` argument of
AudioContext.createBuffer a normative requirement, and fix the exception thrown.

index.html

@@ -514,7 +514,7 @@ <h2 id="AudioContext">The AudioContext Interface</h2>
 
   <dt>AudioBuffer createBuffer()</dt>
   <dd> Creates an AudioBuffer of the given size. The audio data in the buffer will
-  be zero-initialized (silent).  An NOT_SUPPORTED_ERR exception MUST be thrown
+  be zero-initialized (silent).  An INDEX_SIZE_ERR exception MUST be thrown
   if any of the arguments is negative, zero, or outside its nominal range.
   <dl class="parameters">
       <dt>unsigned long numberOfChannels</dt>
@@ -524,8 +524,8 @@ <h2 id="AudioContext">The AudioContext Interface</h2>
       <dd>Determines the size of the buffer in sample-frames.</dd>
       <dt>float sampleRate</dt>
       <dd>Describes the sample-rate of the linear PCM audio data in the buffer in
-      sample-frames per second.  An implementation must support sample-rates in
-      at least the range 22050 to 96000.</dd>
+      sample-frames per second.  An implementation MUST support sample-rates in
+      at least the range 8000 to 192000.</dd>
   </dl>
   </dd>