Support extracting source mapping url defined by //@ sourceMappingURL=<url> comment.

test/mjsunit/debug-compile-event.js

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 63 matching lines @@
         // For source without 'eval' there will be a compile events with the
         // exact source.
         assertEquals(current_source, event_data.script().source());
       }
       // Check that script context is included into the event message.
       var json = event_data.toJSONProtocol();
       var msg = eval('(' + json + ')');
       assertTrue('context' in msg.body.script);
 
       // Check that we pick script name from //@ sourceURL, iff present
-      assertEquals(current_source.indexOf('sourceURL') >= 0 ? 
+      assertEquals(current_source.indexOf('sourceURL') >= 0 ?
                      'myscript.js' : undefined,
                    event_data.script().name());
+
+      // Check that we pick source mapping url from //@ sourceMappingURL, if
+      // present.
+      assertEquals(current_source.indexOf('sourceMappingURL') >= 0 ?
+                     'http://example.com/sourceMapping.json' : undefined,
+                   event_data.script().sourceMappingURL());
     }
   } catch (e) {
     exception = e
   }
 };
 
 
 // Add the debug event listener.
 Debug.setListener(listener);
 
 // Compile different sources.
 compileSource('a=1');
 compileSource('(function(){})');
 compileSource('eval("a=2")');
 source_count++;  // Using eval causes additional compilation event.
 compileSource('eval("eval(\'(function(){return a;})\')")');
 source_count += 2;  // Using eval causes additional compilation event.
 compileSource('JSON.parse(\'{"a":1,"b":2}\')');
 // Using JSON.parse does not causes additional compilation events.
-compileSource('x=1; //@ sourceURL=myscript.js');
+compileSource('x=1; //@ sourceURL=myscript.js\n' +
+              '//@ sourceMappingURL=http://example.com/sourceMapping.json');
 
 // Make sure that the debug event listener was invoked.
 assertFalse(exception, "exception in listener")
 
 // Number of before and after compile events should be the same.
 assertEquals(before_compile_count, after_compile_count);
 
 // Check the actual number of events (no compilation through the API as all
 // source compiled through eval).
 assertEquals(source_count, after_compile_count);
 assertEquals(0, host_compilations);
 assertEquals(source_count, eval_compilations);
 
 Debug.setListener(null);