Set auto breakpoint at various errors

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

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 part of dart._runtime;
 
 throwCastError(object, actual, type) => JS('', '''(() => {
+  $debugger();

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

since you're already in a JS literal, you don't need a function call, you could
just say "debugger;" right? if we don't parse it yet, easy to fix that in
js_ast.

the benefit to the user is one less stack frame.

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

Done.

   $throw_(new $CastErrorImplementation($object,
                                        $typeName($actual),
                                        $typeName($type)));
 })()''');
 
 throwTypeError(object, actual, type) => JS('', '''(() => {
+  $debugger();

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

same for the rest of these

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

Done.

   $throw_(new $TypeErrorImplementation($object,
                                        $typeName($actual),
                                        $typeName($type)));
 })()''');
 
 throwStrongModeCastError(object, actual, type) => JS('', '''(() => {
+  $debugger();
   $throw_(new $StrongModeCastError($object,
                                    $typeName($actual),
                                    $typeName($type)));
 })()''');
 
 throwStrongModeTypeError(object, actual, type) => JS('', '''(() => {
+  $debugger();
   $throw_(new $StrongModeTypeError($object,
                                    $typeName($actual),
                                    $typeName($type)));
 })()''');
 
 throwUnimplementedError(message) => JS('', '''(() => {
+  $debugger();
   $throw_(new $UnimplementedError($message));
 })()''');
 
 throwAssertionError() => JS('', '''(() => {
+  $debugger();
   $throw_(new $AssertionError());
 })()''');
 
 throwNullValueError() => JS('', '''(() => {
   // TODO(vsm): Per spec, we should throw an NSM here.  Technically, we ought
   // to thread through method info, but that uglifies the code and can't
   // actually be queried ... it only affects how the error is printed.
+  $debugger();
   $throw_(new $NoSuchMethodError(null,
       new $Symbol('<Unexpected Null Value>'), null, null, null));
 })()''');