Add support for javascript incompatibility warnings.

runtime/vm/exceptions.h

Index: runtime/vm/exceptions.h
===================================================================
--- runtime/vm/exceptions.h	(revision 35921)
+++ runtime/vm/exceptions.h	(working copy)
@@ -14,6 +14,7 @@
 class Class;
 class DartFrameIterator;
 class Error;
+class ICData;
 class Instance;
 class Object;
 class RawInstance;
@@ -30,6 +31,15 @@
   static void Throw(const Instance& exception);
   static void ReThrow(const Instance& exception, const Instance& stacktrace);
   static void PropagateError(const Error& error);
+
+  static bool MayIssueJSWarning(const ICData& ic_data, bool check_issued);

[srdjan, 2014/05/08 18:11:05]

Please add comment about the arguments.

[regis, 2014/05/09 21:03:42]

Done.
I also removed the check_issue argument, which could make the code more error
prone.

+
+  // Argument ic_data is passed when it is known, e.g. when issuing the warning
+  // from an inline cache miss handler. Otherwise, null is passed when ic_data
+  // is not looked up yet, e.g. when the warning is issued from native code.

[srdjan, 2014/05/08 18:11:05]

Add comment that it can produce errors if appropriate flag is set.

[regis, 2014/05/09 21:03:42]

Done.

+  static void JSWarning(const ICData& ic_data, const char* format, ...)
+      PRINTF_ATTRIBUTE(2, 3);
+
   static RawStacktrace* CurrentStacktrace();
 
   // Helpers to create and throw errors.
@@ -55,6 +65,7 @@
     kIsolateSpawn,
     kIsolateUnhandledException,
     kJavascriptIntegerOverflowError,
+    kJavascriptCompatibilityError,
     kAssertion,
     kCast,
     kType,