Set auto breakpoint at various errors

pkg/dev_compiler/lib/js/legacy/dart_sdk.js

Index: pkg/dev_compiler/lib/js/legacy/dart_sdk.js
diff --git a/pkg/dev_compiler/lib/js/legacy/dart_sdk.js b/pkg/dev_compiler/lib/js/legacy/dart_sdk.js
index 09a7b16ff5cd351df7416455cd531a7661a3c007..d23f542f172191172abbed18e19204576e587526 100644
--- a/pkg/dev_compiler/lib/js/legacy/dart_sdk.js
+++ b/pkg/dev_compiler/lib/js/legacy/dart_sdk.js
@@ -1421,24 +1421,31 @@ dart_library.library('dart_sdk', null, /* Imports */[
     return true;
   };
   dart.throwCastError = function(object, actual, type) {
+    dart.debugger();
     dart.throw(new _js_helper.CastErrorImplementation(object, dart.typeName(actual), dart.typeName(type)));
   };
   dart.throwTypeError = function(object, actual, type) {
+    dart.debugger();
     dart.throw(new _js_helper.TypeErrorImplementation(object, dart.typeName(actual), dart.typeName(type)));
   };
   dart.throwStrongModeCastError = function(object, actual, type) {
+    dart.debugger();
     dart.throw(new _js_helper.StrongModeCastError(object, dart.typeName(actual), dart.typeName(type)));
   };
   dart.throwStrongModeTypeError = function(object, actual, type) {
+    dart.debugger();
     dart.throw(new _js_helper.StrongModeTypeError(object, dart.typeName(actual), dart.typeName(type)));
   };
   dart.throwUnimplementedError = function(message) {
+    dart.debugger();
     dart.throw(new core.UnimplementedError(message));
   };
   dart.throwAssertionError = function() {
+    dart.debugger();
     dart.throw(new core.AssertionError());
   };
   dart.throwNullValueError = function() {
+    dart.debugger();
     dart.throw(new core.NoSuchMethodError(null, new core.Symbol('<Unexpected Null Value>'), null, null, null));
   };
   dart.syncStar = function(gen, E, ...args) {
@@ -1968,10 +1975,15 @@ dart_library.library('dart_sdk', null, /* Imports */[
   dart.getOwnPropertySymbols = function(obj) {
     return Object.getOwnPropertySymbols(obj);
   };
+  dart.debugger = function() {
+    debugger;
+  };
   dart.throwStrongModeError = function(message) {
+    dart.debugger();
     throw new _js_helper.StrongModeErrorImplementation(message);
   };
   dart.throwInternalError = function(message) {
+    dart.debugger();
     throw Error(message);
   };
   dart.getOwnNamesAndSymbols = function(obj) {