Set auto breakpoint at various errors

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/utils.dart

Index: pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/utils.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/utils.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/utils.dart
index 0a3e17621e50da77daa92ebd2b7438590d447386..d7d6c5cbc7d5d02e1cfe516b3df9e15f97c6014c 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/utils.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/utils.dart
@@ -21,14 +21,20 @@ Iterable getOwnPropertySymbols(obj) =>
 
 final hasOwnProperty = JS('', 'Object.prototype.hasOwnProperty');
 
+void debugger() {
+    JS('', 'debugger');
+}
+
 /// This error indicates a strong mode specific failure, other than a type
 /// assertion failure (TypeError) or CastError.
 void throwStrongModeError(String message) {
+  debugger();

[Jennifer Messerly, 2016/11/21 22:16:05]

same here, maybe just inline this:"

    JS('', 'debugger');

that way users get the breakpoint with one less stack frame to jump up.

[vsm, 2016/11/21 22:39:25]

Done.

   JS('', 'throw new #(#);', StrongModeErrorImplementation, message);
 }
 
 /// This error indicates a bug in the runtime or the compiler.
 void throwInternalError(String message) {
+  debugger();
   JS('', 'throw Error(#)', message);
 }