Added support for isolate unhandled exceptions.

sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart

Index: sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart b/sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart
index 9c7b19d2173ff9fa4f679eda9747b65d3369c595..5119cf2ff93523422820c1ccd07caff7c01933da 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart
@@ -103,7 +103,8 @@ patch ReceivePort get port {
   return _lazyPort;
 }
 
-patch SendPort spawnFunction(void topLevelFunction()) {
+patch SendPort spawnFunction(void topLevelFunction(),
+    [bool UnhandledExceptionCallback(IsolateUnhandledException e)]) {
   final name = _IsolateNatives._getJSFunctionName(topLevelFunction);
   if (name == null) {
     throw new UnsupportedError(
@@ -112,7 +113,8 @@ patch SendPort spawnFunction(void topLevelFunction()) {
   return _IsolateNatives._spawn(name, null, false);
 }
 
-patch SendPort spawnUri(String uri) {
+patch SendPort spawnUri(String uri,
+    [bool UnhandledExceptionCallback(IsolateUnhandledException e)]) {
   return _IsolateNatives._spawn(null, uri, false);
 }