Make Exception a class, not an interface, and remove the const constructor.

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index d256c83cbbc8f907e5241a32bbf3fa6f4b651d04..10aea61311d2f7fc51b772493f2d4773ef6a1e4e 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -29795,9 +29795,9 @@ class _TypedArrayFactoryProvider {
   static _U32(arg0, [arg1, arg2]) native "Uint32Array_constructor_Callback";
 
   static Uint8ClampedArray createUint8ClampedArray(int length) => _U8C(length);
-  static Uint8ClampedArray createUint8ClampedArrayUint8ClampedArray_fromList(
+  static Uint8ClampedArray createUint8ClampedArray_fromList(
       List<num> list) => _U8C(ensureNative(list));
-  static Uint8ClampedArray createUint8ClampedArrayUint8ClampedArray_fromBuffer(
+  static Uint8ClampedArray createUint8ClampedArray_fromBuffer(
       ArrayBuffer buffer, [int byteOffset = 0, int length]) =>
       _U8C(buffer, byteOffset, length);
   static _U8C(arg0, [arg1, arg2]) native "Uint8ClampedArray_constructor_Callback";