[Devtools] Added typing to network in prep for removing unrestricted

third_party/WebKit/Source/devtools/front_end/network/RequestHeadersView.js

Index: third_party/WebKit/Source/devtools/front_end/network/RequestHeadersView.js
diff --git a/third_party/WebKit/Source/devtools/front_end/network/RequestHeadersView.js b/third_party/WebKit/Source/devtools/front_end/network/RequestHeadersView.js
index 742ab309d0b83e5cdc7e9a1c58c7c0f88059709c..7b3231ed2135ab9e6e24c632be3af8758210e626 100644
--- a/third_party/WebKit/Source/devtools/front_end/network/RequestHeadersView.js
+++ b/third_party/WebKit/Source/devtools/front_end/network/RequestHeadersView.js
@@ -216,15 +216,16 @@ Network.RequestHeadersView = class extends UI.VBox {
      * @this {Network.RequestHeadersView}
      */
     function toggleViewSource(event) {
-      paramsTreeElement._viewSource = !paramsTreeElement._viewSource;
+      paramsTreeElement[Network.RequestHeadersView._viewSourceSymbol] =
+          !paramsTreeElement[Network.RequestHeadersView._viewSourceSymbol];
       this._refreshParams(title, params, sourceText, paramsTreeElement);
       event.consume();
     }
 
-    paramsTreeElement.listItemElement.appendChild(
-        this._createViewSourceToggle(paramsTreeElement._viewSource, toggleViewSource.bind(this)));
+    paramsTreeElement.listItemElement.appendChild(this._createViewSourceToggle(
+        paramsTreeElement[Network.RequestHeadersView._viewSourceSymbol], toggleViewSource.bind(this)));
 
-    if (paramsTreeElement._viewSource) {
+    if (paramsTreeElement[Network.RequestHeadersView._viewSourceSymbol]) {
       this._populateTreeElementWithSourceText(paramsTreeElement, sourceText);
       return;
     }
@@ -270,13 +271,15 @@ Network.RequestHeadersView = class extends UI.VBox {
      * @this {Network.RequestHeadersView}
      */
     function toggleViewSource(event) {
-      treeElement._viewSource = !treeElement._viewSource;
+      treeElement[Network.RequestHeadersView._viewSourceSymbol] =
+          !treeElement[Network.RequestHeadersView._viewSourceSymbol];
       this._refreshRequestJSONPayload(parsedObject, sourceText);
       event.consume();
     }
 
-    listItem.appendChild(this._createViewSourceToggle(treeElement._viewSource, toggleViewSource.bind(this)));
-    if (treeElement._viewSource) {
+    listItem.appendChild(this._createViewSourceToggle(
+        treeElement[Network.RequestHeadersView._viewSourceSymbol], toggleViewSource.bind(this)));
+    if (treeElement[Network.RequestHeadersView._viewSourceSymbol]) {
       this._populateTreeElementWithSourceText(this._requestPayloadCategory, sourceText);
     } else {
       var object = SDK.RemoteObject.fromLocalObject(parsedObject);
@@ -496,6 +499,8 @@ Network.RequestHeadersView = class extends UI.VBox {
   }
 };
 
+Network.RequestHeadersView._viewSourceSymbol = Symbol('ViewSource');
+
 /**
  * @unrestricted
  */