Make all DDC internal stack traces apply source maps.

pkg/dev_compiler/tool/input_sdk/private/debugger.dart

Index: pkg/dev_compiler/tool/input_sdk/private/debugger.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/debugger.dart b/pkg/dev_compiler/tool/input_sdk/private/debugger.dart
index 7fbc2deb39f65d19eacbff0c57e7d69bfb93cf87..c4c65a09b3a1935cf806926e465dab5374ceb8e2 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/debugger.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/debugger.dart
@@ -850,6 +850,18 @@ class TypeFormatter implements Formatter {
   List<NameValuePair> children(object) => [];
 }
 
+typedef String StackTraceMapper(String stackTrace);
+
+/// Hook for other parts of the SDK To use to map JS stack traces to Dart
+/// stack traces.
+///
+/// Raw JS stack traces are used if $dartStackTraceUtility has not been
+/// specified.
+StackTraceMapper get stackTraceMapper {
+  var _util = JS('', r'dart.global.$dartStackTraceUtility');
+  return _util != null ? JS('StackTraceMapper', '#.mapper', _util) : null;
+}
+
 /// This entry point is automatically invoked by the code generated by
 /// Dart Dev Compiler
 registerDevtoolsFormatter() {