Update tests to remove treeElementSymbol usage

DevTools frontend CL: https://crrev.com/c/2438385

Bug: chromium:1133675
Change-Id: I47220215232540c94733bec2ceb64e40c1021d12
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2440664Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Changhao Han <changhaohan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812632}

third_party/blink/web_tests/TestExpectations

@@ -6606,10 +6606,6 @@ crbug.com/1094436 http/tests/devtools/persistence/automapping-urlencoded-paths.j
 crbug.com/1094436 http/tests/devtools/sources/debugger-ui/snippet-edit-breakpoint.js [ Pass Timeout ]
 crbug.com/1094436 http/tests/devtools/sources/debugger/navigator-view.js [ Pass Failure Crash ]
 
-# Temporarily disable tests to allow refactoring DevTools ad hoc fields in DOMNode
-crbug.com/1133675 http/tests/devtools/elements/elements-child-node-count-mismatch.js [ Pass Failure ]
-crbug.com/1133675 http/tests/devtools/elements/move-node.js [ Pass Failure Timeout ]
-
 # Sheriff 2020-07-20
 crbug.com/1107572 [ Mac ] http/tests/devtools/tracing/timeline-layout/timeline-layout-with-invalidations.js [ Pass Failure ]
 crbug.com/1107572 [ Mac ] http/tests/devtools/tracing/timeline-style/timeline-style-recalc-with-invalidations.js [ Pass Failure ]

third_party/blink/web_tests/http/tests/devtools/elements/elements-child-node-count-mismatch.js

@@ -32,7 +32,7 @@
 
   function afterExpand() {
     ElementsTestRunner.selectNodeWithId('body', node => {
-      const treeElement = node[treeOutline.treeElementSymbol()];
+      const treeElement = treeOutline.treeElementByNode.get(node);
       TestRunner.addResult(`AFTER EXPAND: TreeElement childCount: ${treeElement.childCount()}`);
 
       var selectedElement = treeOutline.selectedTreeElement;

third_party/blink/web_tests/http/tests/devtools/elements/move-node.js

@@ -43,8 +43,8 @@
 
       var child2 = ElementsTestRunner.expandedNodeWithId('child2');
       var child4 = ElementsTestRunner.expandedNodeWithId('child4');
-      treeOutline._treeElementBeingDragged = child2[treeOutline._treeElementSymbol];
-      var treeElementToDropOn = child4[treeOutline._treeElementSymbol];
+      treeOutline._treeElementBeingDragged = treeOutline.treeElementByNode.get(child2);
+      var treeElementToDropOn = treeOutline.treeElementByNode.get(child4);
       treeOutline._doMove(treeElementToDropOn);
     }
   ]);