Avoid load-time uses of Uint8Array.

This is inteded to fix a couple of the load-time exceptions seen
when loading the library on IE9.  Eliminating load-time exceptions
will make it possible to use isBrowserSupported() as intended, to
avoid use of the library on older browsers.

Issue #87

Change-Id: I993d4f955e80a7401bea182ae90df43a8a022ca2

lib/polyfill/patchedmediakeys_v01b.js

@@ -41,6 +41,11 @@ shaka.polyfill.PatchedMediaKeys.v01b.install = function() {
   // Alias.
   var v01b = shaka.polyfill.PatchedMediaKeys.v01b;
 
+  // Construct fake key ID.  This is not done at load-time to avoid exceptions
+  // on unsupported browsers.
+  v01b.MediaKeyStatusMap.KEY_ID_ =
+      shaka.util.Uint8ArrayUtils.fromString('FAKE_KEY_ID');
+
   // Install patches.
   Navigator.prototype.requestMediaKeySystemAccess =
       v01b.requestMediaKeySystemAccess;
@@ -889,8 +894,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap = function() {
  * @const {!Uint8Array}
  * @private
  */
-shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.KEY_ID_ =
-    shaka.util.Uint8ArrayUtils.fromString('FAKE_KEY_ID');
+shaka.polyfill.PatchedMediaKeys.v01b.MediaKeyStatusMap.KEY_ID_;
 
 
 /**

lib/util/ebml_parser.js

@@ -34,19 +34,26 @@ shaka.util.EbmlParser = function(dataView) {
   this.reader_ = new shaka.util.DataViewReader(
       dataView,
       shaka.util.DataViewReader.Endianness.BIG_ENDIAN);
+
+  // If not already constructed, build a list of EBML dynamic size constants.
+  // This is not done at load-time to avoid exceptions on unsupported browsers.
+  if (!shaka.util.EbmlParser.DYNAMIC_SIZES) {
+    shaka.util.EbmlParser.DYNAMIC_SIZES = [
+      new Uint8Array([0xff]),
+      new Uint8Array([0x7f, 0xff]),
+      new Uint8Array([0x3f, 0xff, 0xff]),
+      new Uint8Array([0x1f, 0xff, 0xff, 0xff]),
+      new Uint8Array([0x0f, 0xff, 0xff, 0xff, 0xff]),
+      new Uint8Array([0x07, 0xff, 0xff, 0xff, 0xff, 0xff]),
+      new Uint8Array([0x03, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff]),
+      new Uint8Array([0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff])
+    ];
+  }
 };
 
 
 /** @const {!Array.<!Uint8Array>} */
-shaka.util.EbmlParser.DYNAMIC_SIZES = [
-  new Uint8Array([0xff]),
-  new Uint8Array([0x7f, 0xff]),
-  new Uint8Array([0x3f, 0xff, 0xff]),
-  new Uint8Array([0x1f, 0xff, 0xff, 0xff]),
-  new Uint8Array([0x0f, 0xff, 0xff, 0xff, 0xff]),
-  new Uint8Array([0x07, 0xff, 0xff, 0xff, 0xff, 0xff]),
-  new Uint8Array([0x03, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff]),
-  new Uint8Array([0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff])];
+shaka.util.EbmlParser.DYNAMIC_SIZES;
 
 
 /**