[wasm] [asmjs] Route asm.js warnings to the dev console.

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index ccac0244da949d0f762b0411c4c24e5f60f5c8a8..bf3a9dbee32ae65aeca6830666a796e6f38fef8f 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -5710,6 +5710,10 @@ typedef void (*OOMErrorCallback)(const char* location, bool is_heap_oom);
 
 typedef void (*MessageCallback)(Local<Message> message, Local<Value> error);
 
+// --- Warnings ---
+
+typedef void (*AsmJsWarningCallback)(Local<Message> message);
+
 // --- Tracing ---
 
 typedef void (*LogEventCallback)(const char* name, int event);
@@ -7067,6 +7071,9 @@ class V8_EXPORT Isolate {
   /** Set the callback to invoke in case of OOM errors. */
   void SetOOMErrorHandler(OOMErrorCallback that);
 
+  /** Set the callback to invoke in case of AsmJS validation errors. */
+  void SetAsmJsWarningHandler(AsmJsWarningCallback that);
+
   /**
    * Set the callback to invoke to check if code generation from
    * strings should be allowed.