[Devtools] Lazily build reverse mappings

third_party/WebKit/Source/devtools/front_end/bindings/CompilerScriptMapping.js

 /*
  * Copyright (C) 2012 Google Inc. 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
@@ skipping 211 matching lines @@
         if (this._scriptForSourceMap.get(sourceMap)) {
             this._sourceMapForScriptId.set(script.scriptId, sourceMap);
             this._debuggerWorkspaceBinding.updateLocations(script);
             return;
         }
 
         this._sourceMapForScriptId.set(script.scriptId, sourceMap);
         this._scriptForSourceMap.set(sourceMap, script);
 
         // Report sources.
-        var sourceURLs = sourceMap.sourceURLs();
         var missingSources = [];
-        for (var i = 0; i < sourceURLs.length; ++i) {
-            var sourceURL = sourceURLs[i];
+        for (var sourceURL of sourceMap.sourceURLs()) {
             if (this._sourceMapForURL.get(sourceURL))
                 continue;
             this._sourceMapForURL.set(sourceURL, sourceMap);
             var uiSourceCode = this._networkMapping.uiSourceCodeForScriptURL(sourceURL, script);
             if (!uiSourceCode) {
                 var contentProvider = sourceMap.sourceContentProvider(sourceURL, WebInspector.resourceTypes.SourceMapScript);
                 uiSourceCode = this._networkProject.addFile(contentProvider, WebInspector.ResourceTreeFrame.fromScript(script), script.isContentScript());
                 uiSourceCode[WebInspector.CompilerScriptMapping._originSymbol] = script.sourceURL;
             }
             if (uiSourceCode) {
@@ skipping 110 matching lines @@
     {
         /**
          * @param {!WebInspector.TextSourceMap} sourceMap
          * @this {WebInspector.CompilerScriptMapping}
          */
         function unbindSourceMapSources(sourceMap)
         {
             var script = this._scriptForSourceMap.get(sourceMap);
             if (!script)
                 return;
-            var sourceURLs = sourceMap.sourceURLs();
-            for (var i = 0; i < sourceURLs.length; ++i) {
-                var uiSourceCode = this._networkMapping.uiSourceCodeForScriptURL(sourceURLs[i], script);
+            for (var sourceURL of sourceMap.sourceURLs()) {
+                var uiSourceCode = this._networkMapping.uiSourceCodeForScriptURL(sourceURL, script);
                 if (uiSourceCode)
                     this._unbindUISourceCode(uiSourceCode);
             }
         }
 
         this._sourceMapForURL.valuesArray().forEach(unbindSourceMapSources.bind(this));
 
         this._sourceMapLoadingPromises.clear();
         this._sourceMapForScriptId.clear()
         this._scriptForSourceMap.clear();
         this._sourceMapForURL.clear();
     },
 
     dispose: function()
     {
         WebInspector.EventTarget.removeEventListeners(this._eventListeners);
         this._debuggerReset();
         this._stubProject.dispose();
     }
 }
 
 /**
  * @param {!WebInspector.Target} target
  * @return {string}
  */
 WebInspector.CompilerScriptMapping.projectIdForTarget = function(target)
 {
     return "compiler-script-project:" + target.id();
 }