Introduce InterfaceEndpointClient(IEC), InterfaceEndpointHandle and

mojo/public/js/codec.js

Index: mojo/public/js/codec.js
diff --git a/mojo/public/js/codec.js b/mojo/public/js/codec.js
index ff5d31a08e5fef423d1a2f2230377bbdf8b8d8ec..ce58a8cfd4aea874d6b752d9f8efe47f28268037 100644
--- a/mojo/public/js/codec.js
+++ b/mojo/public/js/codec.js
@@ -453,6 +453,10 @@ define("mojo/public/js/codec", [
     return this.buffer.getUint32(kMessageFlagsOffset);
   };
 
+  Message.prototype.getInterfaceId = function() {
+    return this.buffer.getUint32(kMessageInterfaceIdOffset);
+  };
+
   Message.prototype.isResponse = function() {
     return (this.getFlags() & kMessageIsResponse) != 0;
   };
@@ -466,6 +470,10 @@ define("mojo/public/js/codec", [
     this.buffer.setUint64(kMessageRequestIDOffset, requestID);
   };
 
+  Message.prototype.setInterfaceId = function(interfaceId) {
+    this.buffer.setUint32(kMessageInterfaceIdOffset, interfaceId);
+  };
+
 
   // MessageBuilder -----------------------------------------------------------
 
@@ -537,10 +545,6 @@ define("mojo/public/js/codec", [
     this.payloadSize = message.buffer.byteLength - messageHeaderSize;
     var version = this.decoder.readUint32();
     var interface_id = this.decoder.readUint32();
-    if (interface_id != 0) {
-      throw new Error("Receiving non-zero interface ID. Associated interfaces " +
-                      "are not yet supported.");
-    }
     this.messageName = this.decoder.readUint32();
     this.flags = this.decoder.readUint32();
     // Skip the padding.