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 7820c1b69fa0357dd023703cc900986fb13b168e..df096198a51a9db335fa676574cdb98e7b8baf2b 100644
--- a/pkg/dev_compiler/lib/js/legacy/dart_sdk.js
+++ b/pkg/dev_compiler/lib/js/legacy/dart_sdk.js
@@ -1688,36 +1688,47 @@ dart_library.library('dart_sdk', null, /* Imports */[
     }
     return true;
   };
+  dart.trapRuntimeErrors = function(flag) {
+    dart._trapRuntimeErrors = flag;
+  };
   dart.throwCastError = function(object, actual, type) {
-    debugger;
-    dart.throw(new _js_helper.CastErrorImplementation(object, dart.typeName(actual), dart.typeName(type)));
+    var found = dart.typeName(actual);
+    var expected = dart.typeName(type);
+    if (dart._trapRuntimeErrors) debugger;
+    dart.throw(new _js_helper.CastErrorImplementation(object, found, expected));
   };
   dart.throwTypeError = function(object, actual, type) {
-    debugger;
-    dart.throw(new _js_helper.TypeErrorImplementation(object, dart.typeName(actual), dart.typeName(type)));
+    var found = dart.typeName(actual);
+    var expected = dart.typeName(type);
+    if (dart._trapRuntimeErrors) debugger;
+    dart.throw(new _js_helper.TypeErrorImplementation(object, found, expected));
   };
   dart.throwStrongModeCastError = function(object, actual, type) {
-    debugger;
-    dart.throw(new _js_helper.StrongModeCastError(object, dart.typeName(actual), dart.typeName(type)));
+    var found = dart.typeName(actual);
+    var expected = dart.typeName(type);
+    if (dart._trapRuntimeErrors) debugger;
+    dart.throw(new _js_helper.StrongModeCastError(object, found, expected));
   };
   dart.throwStrongModeTypeError = function(object, actual, type) {
-    debugger;
-    dart.throw(new _js_helper.StrongModeTypeError(object, dart.typeName(actual), dart.typeName(type)));
+    var found = dart.typeName(actual);
+    var expected = dart.typeName(type);
+    if (dart._trapRuntimeErrors) debugger;
+    dart.throw(new _js_helper.StrongModeTypeError(object, found, expected));
   };
   dart.throwUnimplementedError = function(message) {
-    debugger;
+    if (dart._trapRuntimeErrors) debugger;
     dart.throw(new core.UnimplementedError(message));
   };
   dart.throwAssertionError = function(message) {
     if (message === void 0) message = null;
     return (() => {
-      debugger;
+      if (dart._trapRuntimeErrors) debugger;
       let error = message != null ? new _js_helper.AssertionErrorWithMessage(message()) : new core.AssertionError();
       dart.throw(error);
     })();
   };
   dart.throwNullValueError = function() {
-    debugger;
+    if (dart._trapRuntimeErrors) debugger;
     dart.throw(new core.NoSuchMethodError(null, new core.Symbol('<Unexpected Null Value>'), null, null, null));
   };
   dart.syncStar = function(gen, E, ...args) {
@@ -2249,11 +2260,11 @@ dart_library.library('dart_sdk', null, /* Imports */[
     return Object.getOwnPropertySymbols(obj);
   };
   dart.throwStrongModeError = function(message) {
-    debugger;
+    if (dart.test(dart._trapRuntimeErrors)) debugger;
     throw new _js_helper.StrongModeErrorImplementation(message);
   };
   dart.throwInternalError = function(message) {
-    debugger;
+    if (dart.test(dart._trapRuntimeErrors)) debugger;
     throw Error(message);
   };
   dart.getOwnNamesAndSymbols = function(obj) {
@@ -2664,6 +2675,7 @@ dart_library.library('dart_sdk', null, /* Imports */[
   };
   dart._typeFormalCount = Symbol("_typeFormalCount");
   dart.isSubtype = dart._subtypeMemo((t1, t2) => t1 === t2 || dart._isSubtype(t1, t2, true));
+  dart._trapRuntimeErrors = true;
   dart._jsIterator = Symbol("_jsIterator");
   dart._current = Symbol("_current");
   dart._AsyncStarStreamController = class _AsyncStarStreamController {