Add support to trace warnings in TraceBuffer.

runtime/vm/exceptions.h

 // Copyright (c) 2011, 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.
 
 #ifndef VM_EXCEPTIONS_H_
 #define VM_EXCEPTIONS_H_
 
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
 
@@ skipping 17 matching lines @@
  public:
   static const char* kCastErrorDstName;
 
   static void Throw(const Instance& exception);
   static void ReThrow(const Instance& exception, const Instance& stacktrace);
   static void PropagateError(const Error& error);
 
   // Report a Javascript compatibility warning at the call site given by
   // caller_frame. Note that a JavascriptCompatibilityError is thrown
   // if --warning_as_error is specified.
+  // Also calls TraceJSWarningV below.
   static void JSWarning(StackFrame* caller_frame, const char* format, ...)
       PRINTF_ATTRIBUTE(2, 3);
 
+  // Emit a Javascript compatibility warning to the current trace buffer.
+  static void TraceJSWarningF(const Script& script, intptr_t token_pos,
+                              const char* format, ...) PRINTF_ATTRIBUTE(3, 4);
+  static void TraceJSWarningV(const Script& script, intptr_t token_pos,
+                              const char* format, va_list args);
+
   static RawStacktrace* CurrentStacktrace();
 
   // Helpers to create and throw errors.
   static RawScript* GetCallerScript(DartFrameIterator* iterator);
   static RawInstance* NewInstance(const char* class_name);
   static void CreateAndThrowTypeError(intptr_t location,
                                       const String& src_type_name,
                                       const String& dst_type_name,
                                       const String& dst_name,
                                       const String& error_msg);
@@ skipping 30 matching lines @@
   // otherwise returns a RawError.
   static RawObject* Create(ExceptionType type, const Array& arguments);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(Exceptions);
 };
 
 }  // namespace dart
 
 #endif  // VM_EXCEPTIONS_H_