Rename externs/html5.js to externs/closure-compiler.js

Add add a fix for issues:
  * https://code.google.com/p/closure-compiler/issues/detail?id=1084
  * https://code.google.com/p/closure-compiler/issues/detail?id=1088

externs/closure-compiler.js

@@ -0,0 +1,38 @@
+/**
+ * @fileoverview Definitions for externs that are either missing or incorrect
+ * in the current release version of the closure compiler we use.
+ *
+ * The entries must be removed once they are available/correct in the
+ * version we use.
+ *
+ * @externs
+ */
+
+// @see https://code.google.com/p/closure-compiler/issues/detail?id=1060
+
+/** @type {Date} */
+HTMLInputElement.prototype.valueAsDate;
+
+/** @type {number} */
+HTMLInputElement.prototype.valueAsNumber;
+
+
+// @see https://code.google.com/p/closure-compiler/issues/detail?id=1084
+
+/** @type {?number} */
+DeviceRotationRate.prototype.alpha;
+
+/** @type {?number} */
+DeviceRotationRate.prototype.beta;
+
+/** @type {?number} */
+DeviceRotationRate.prototype.gamma;
+
+
+// @see https://code.google.com/p/closure-compiler/issues/detail?id=1088
+
+/** @type {?number} */
+DeviceOrientationEvent.prototype.webkitCompassAccuracy;
+
+/** @type {?number} */
+DeviceOrientationEvent.prototype.webkitCompassHeading;