[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 e5ff0c0332b5035e9d065103054c0d7df9eb9b6e..86aa8b7d2d0d3bce9b0163ae0cfd7432776508b1 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -1478,6 +1478,11 @@ class V8_EXPORT Message {
   int GetEndPosition() const;
 
   /**
+   * Returns the error level of the message.
+   */
+  int ErrorLevel() const;
+
+  /**
    * Returns the index within the line of the first character where
    * the error occurred.
    */
@@ -6451,6 +6456,16 @@ class V8_EXPORT Isolate {
     kUseCounterFeatureCount  // This enum value must be last.
   };
 
+  enum MessageErrorLevel {
+    kMessageLog = (1 << 0),
+    kMessageDebug = (1 << 1),
+    kMessageInfo = (1 << 2),
+    kMessageError = (1 << 3),
+    kMessageWarning = (1 << 4),
+    kMessageAll = kMessageLog | kMessageDebug | kMessageInfo | kMessageError |
+                  kMessageWarning,
+  };
+
   typedef void (*UseCounterCallback)(Isolate* isolate,
                                      UseCounterFeature feature);
 
@@ -7055,7 +7070,7 @@ class V8_EXPORT Isolate {
   bool IsDead();
 
   /**
-   * Adds a message listener.
+   * Adds a message listener (errors only).
    *
    * The same message listener can be added more than once and in that
    * case it will be called more than once for each message.
@@ -7067,6 +7082,21 @@ class V8_EXPORT Isolate {
                           Local<Value> data = Local<Value>());
 
   /**
+   * Adds a message listener.
+   *
+   * The same message listener can be added more than once and in that
+   * case it will be called more than once for each message.
+   *
+   * If data is specified, it will be passed to the callback when it is called.
+   * Otherwise, the exception object will be passed to the callback instead.
+   *
+   * A listener can listen for particular error levels by providing a mask.
+   */
+  bool AddMessageListenerWithErrorLevel(MessageCallback that,
+                                        int message_levels,
+                                        Local<Value> data = Local<Value>());
+
+  /**
    * Remove all message listeners from the specified callback function.
    */
   void RemoveMessageListeners(MessageCallback that);