DevTools: migrate from external Maps to symbols in the bindings objects.

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

Index: third_party/WebKit/Source/devtools/front_end/bindings/DebuggerWorkspaceBinding.js
diff --git a/third_party/WebKit/Source/devtools/front_end/bindings/DebuggerWorkspaceBinding.js b/third_party/WebKit/Source/devtools/front_end/bindings/DebuggerWorkspaceBinding.js
index cecb966e3c26a179b4893840780cd454d64721a1..ebc3a428f041221c8ee68bc8d6543a02aa087a82 100644
--- a/third_party/WebKit/Source/devtools/front_end/bindings/DebuggerWorkspaceBinding.js
+++ b/third_party/WebKit/Source/devtools/front_end/bindings/DebuggerWorkspaceBinding.js
@@ -86,7 +86,7 @@ Bindings.DebuggerWorkspaceBinding = class extends Common.Object {
    * @return {!Bindings.DebuggerSourceMapping}
    */
   popSourceMapping(script) {
-    var info = this._infoForScript(script.target(), script.scriptId);
+    var info = this._infoForScript(script);
     console.assert(info);
     return info._popSourceMapping();
   }
@@ -106,7 +106,7 @@ Bindings.DebuggerWorkspaceBinding = class extends Common.Object {
    * @param {!SDK.Script} script
    */
   updateLocations(script) {
-    var info = this._infoForScript(script.target(), script.scriptId);
+    var info = this._infoForScript(script);
     if (info)
       info._updateLocations();
   }
@@ -118,7 +118,7 @@ Bindings.DebuggerWorkspaceBinding = class extends Common.Object {
    * @return {!Bindings.DebuggerWorkspaceBinding.Location}
    */
   createLiveLocation(rawLocation, updateDelegate, locationPool) {
-    var info = this._infoForScript(rawLocation.target(), rawLocation.scriptId);
+    var info = this._infoForScript(rawLocation.script());
     console.assert(info);
     var location =
         new Bindings.DebuggerWorkspaceBinding.Location(info._script, rawLocation, this, updateDelegate, locationPool);
@@ -162,7 +162,7 @@ Bindings.DebuggerWorkspaceBinding = class extends Common.Object {
    * @return {!Workspace.UILocation}
    */
   rawLocationToUILocation(rawLocation) {
-    var info = this._infoForScript(rawLocation.target(), rawLocation.scriptId);
+    var info = this._infoForScript(rawLocation.script());
     console.assert(info);
     return info._rawLocationToUILocation(rawLocation);
   }
@@ -280,25 +280,22 @@ Bindings.DebuggerWorkspaceBinding = class extends Common.Object {
    * @return {!Bindings.DebuggerWorkspaceBinding.ScriptInfo}
    */
   _ensureInfoForScript(script) {
-    var scriptDataMap = this._targetToData.get(script.target()).scriptDataMap;
-    var info = scriptDataMap.get(script.scriptId);
+    var info = script[Bindings.DebuggerWorkspaceBinding._scriptInfoSymbol];
     if (!info) {
       info = new Bindings.DebuggerWorkspaceBinding.ScriptInfo(script);
-      scriptDataMap.set(script.scriptId, info);
+      script[Bindings.DebuggerWorkspaceBinding._scriptInfoSymbol] = info;
     }
     return info;
   }
 
   /**
-   * @param {!SDK.Target} target
-   * @param {string} scriptId
+   * @param {?SDK.Script} script
    * @return {?Bindings.DebuggerWorkspaceBinding.ScriptInfo}
    */
-  _infoForScript(target, scriptId) {
-    var data = this._targetToData.get(target);
-    if (!data)
+  _infoForScript(script) {
+    if (!script)
       return null;
-    return data.scriptDataMap.get(scriptId) || null;
+    return script[Bindings.DebuggerWorkspaceBinding._scriptInfoSymbol] || null;
   }
 
   /**
@@ -314,7 +311,7 @@ Bindings.DebuggerWorkspaceBinding = class extends Common.Object {
    * @param {!Bindings.DebuggerWorkspaceBinding.Location} location
    */
   _removeLiveLocation(location) {
-    var info = this._infoForScript(location._script.target(), location._script.scriptId);
+    var info = this._infoForScript(location._script);
     if (info)
       info._removeLocation(location);
   }
@@ -328,6 +325,9 @@ Bindings.DebuggerWorkspaceBinding = class extends Common.Object {
   }
 };
 
+Bindings.DebuggerWorkspaceBinding._scriptInfoSymbol = Symbol('scriptDataMap');
+Bindings.DebuggerWorkspaceBinding._sourceMappingSymbol = Symbol('sourceMapping');
+
 /**
  * @unrestricted
  */
@@ -340,9 +340,6 @@ Bindings.DebuggerWorkspaceBinding.TargetData = class {
     this._debuggerModel = debuggerModel;
     this._debuggerWorkspaceBinding = debuggerWorkspaceBinding;
 
-    /** @type {!Map.<string, !Bindings.DebuggerWorkspaceBinding.ScriptInfo>} */
-    this.scriptDataMap = new Map();
-
     /** @type {!Set.<!Bindings.DebuggerWorkspaceBinding.Location>} */
     this.callFrameLocations = new Set();
 
@@ -354,13 +351,11 @@ Bindings.DebuggerWorkspaceBinding.TargetData = class {
         debuggerModel, workspace, Bindings.NetworkProject.forTarget(this._debuggerModel.target()),
         debuggerWorkspaceBinding);
 
-    /** @type {!Map.<!Workspace.UISourceCode, !Bindings.DebuggerSourceMapping>} */
-    this._uiSourceCodeToSourceMapping = new Map();
-
     debuggerModel.setBeforePausedCallback(this._beforePaused.bind(this));
     this._eventListeners = [
       debuggerModel.addEventListener(SDK.DebuggerModel.Events.ParsedScriptSource, this._parsedScriptSource, this),
-      debuggerModel.addEventListener(SDK.DebuggerModel.Events.FailedToParseScriptSource, this._parsedScriptSource, this)
+      debuggerModel.addEventListener(
+          SDK.DebuggerModel.Events.FailedToParseScriptSource, this._parsedScriptSource, this),
     ];
   }
 
@@ -389,19 +384,20 @@ Bindings.DebuggerWorkspaceBinding.TargetData = class {
    * @param {?Bindings.DebuggerSourceMapping} sourceMapping
    */
   _setSourceMapping(uiSourceCode, sourceMapping) {
-    if (this._uiSourceCodeToSourceMapping.get(uiSourceCode) === sourceMapping)
+    if (uiSourceCode[Bindings.DebuggerWorkspaceBinding._sourceMappingSymbol] === sourceMapping)
       return;
 
     if (sourceMapping)
-      this._uiSourceCodeToSourceMapping.set(uiSourceCode, sourceMapping);
+      uiSourceCode[Bindings.DebuggerWorkspaceBinding._sourceMappingSymbol] = sourceMapping;
     else
-      this._uiSourceCodeToSourceMapping.remove(uiSourceCode);
+      delete uiSourceCode[Bindings.DebuggerWorkspaceBinding._sourceMappingSymbol];
 
-    this._debuggerWorkspaceBinding.dispatchEventToListeners(Bindings.DebuggerWorkspaceBinding.Events.SourceMappingChanged, {
-      uiSourceCode: uiSourceCode,
-      target: this._debuggerModel.target(),
-      isIdentity: sourceMapping ? sourceMapping.isIdentity() : false
-    });
+    this._debuggerWorkspaceBinding.dispatchEventToListeners(
+        Bindings.DebuggerWorkspaceBinding.Events.SourceMappingChanged, {
+          uiSourceCode: uiSourceCode,
+          target: this._debuggerModel.target(),
+          isIdentity: sourceMapping ? sourceMapping.isIdentity() : false
+        });
   }
 
   /**
@@ -411,7 +407,7 @@ Bindings.DebuggerWorkspaceBinding.TargetData = class {
    * @return {?SDK.DebuggerModel.Location}
    */
   _uiLocationToRawLocation(uiSourceCode, lineNumber, columnNumber) {
-    var sourceMapping = this._uiSourceCodeToSourceMapping.get(uiSourceCode);
+    var sourceMapping = uiSourceCode[Bindings.DebuggerWorkspaceBinding._sourceMappingSymbol];
     return sourceMapping ? sourceMapping.uiLocationToRawLocation(uiSourceCode, lineNumber, columnNumber) : null;
   }
 
@@ -421,7 +417,7 @@ Bindings.DebuggerWorkspaceBinding.TargetData = class {
    * @return {boolean}
    */
   _uiLineHasMapping(uiSourceCode, lineNumber) {
-    var sourceMapping = this._uiSourceCodeToSourceMapping.get(uiSourceCode);
+    var sourceMapping = uiSourceCode[Bindings.DebuggerWorkspaceBinding._sourceMappingSymbol];
     return sourceMapping ? sourceMapping.uiLineHasMapping(uiSourceCode, lineNumber) : true;
   }
 
@@ -429,7 +425,7 @@ Bindings.DebuggerWorkspaceBinding.TargetData = class {
    * @param {!Workspace.UISourceCode} uiSourceCode
    */
   _uiSourceCodeRemoved(uiSourceCode) {
-    this._uiSourceCodeToSourceMapping.remove(uiSourceCode);
+    delete uiSourceCode[Bindings.DebuggerWorkspaceBinding._sourceMappingSymbol];
   }
 
   _dispose() {
@@ -438,7 +434,6 @@ Bindings.DebuggerWorkspaceBinding.TargetData = class {
     this._compilerMapping.dispose();
     this._resourceMapping.dispose();
     this._defaultMapping.dispose();
-    this._uiSourceCodeToSourceMapping.clear();
   }
 };
 
@@ -457,19 +452,21 @@ Bindings.DebuggerWorkspaceBinding.ScriptInfo = class {
    */
   constructor(script) {
     this._script = script;
-
-    /** @type {!Array.<!Bindings.DebuggerSourceMapping>} */
-    this._sourceMappings = [];
-
-    /** @type {!Set<!Bindings.LiveLocation>} */
-    this._locations = new Set();
+    // We create a lot of these, do not add arrays/collections/expensive data structures.
   }
 
   /**
    * @param {!Bindings.DebuggerSourceMapping} sourceMapping
    */
   _pushSourceMapping(sourceMapping) {
-    this._sourceMappings.push(sourceMapping);
+    if (this._sourceMapping) {
+      if (!this._backupMappings) {
+        /** @type {!Array.<!Bindings.DebuggerSourceMapping>} */
+        this._backupMappings = [];
+      }
+      this._backupMappings.push(this._sourceMapping);
+    }
+    this._sourceMapping = sourceMapping;
     this._updateLocations();
   }
 
@@ -477,7 +474,8 @@ Bindings.DebuggerWorkspaceBinding.ScriptInfo = class {
    * @return {!Bindings.DebuggerSourceMapping}
    */
   _popSourceMapping() {
-    var sourceMapping = this._sourceMappings.pop();
+    var sourceMapping = this._sourceMapping;
+    this._sourceMapping = this._backupMappings ? this._backupMappings.pop() : undefined;
     this._updateLocations();
     return sourceMapping;
   }
@@ -486,6 +484,10 @@ Bindings.DebuggerWorkspaceBinding.ScriptInfo = class {
    * @param {!Bindings.LiveLocation} location
    */
   _addLocation(location) {
+    if (!this._locations) {
+      /** @type {!Set<!Bindings.LiveLocation>} */
+      this._locations = new Set();
+    }
     this._locations.add(location);
     location.update();
   }
@@ -494,10 +496,14 @@ Bindings.DebuggerWorkspaceBinding.ScriptInfo = class {
    * @param {!Bindings.LiveLocation} location
    */
   _removeLocation(location) {
+    if (!this._locations)
+      return;
     this._locations.delete(location);
   }
 
   _updateLocations() {
+    if (!this._locations)
+      return;
     for (var location of this._locations)
       location.update();
   }
@@ -507,9 +513,11 @@ Bindings.DebuggerWorkspaceBinding.ScriptInfo = class {
    * @return {!Workspace.UILocation}
    */
   _rawLocationToUILocation(rawLocation) {
-    var uiLocation;
-    for (var i = this._sourceMappings.length - 1; !uiLocation && i >= 0; --i)
-      uiLocation = this._sourceMappings[i].rawLocationToUILocation(rawLocation);
+    var uiLocation = this._sourceMapping ? this._sourceMapping.rawLocationToUILocation(rawLocation) : null;
+    if (!uiLocation && this._backupMappings) {
+      for (var i = this._backupMappings.length - 1; !uiLocation && i >= 0; --i)
+        uiLocation = this._backupMappings[i].rawLocationToUILocation(rawLocation);
+    }
     console.assert(uiLocation, 'Script raw location cannot be mapped to any UI location.');
     return /** @type {!Workspace.UILocation} */ (uiLocation);
   }