DevTools: Don't crash when text nodes are edited to be whitespace

DevTools ignores whitespace-only text nodes. But if a text node
that previously had text becomes whitespace-only, no childNodeRemoved
event is fired and DevTools would get confused.

Bug: 880372
Change-Id: I8f740a6e32d1c1a15a32443a2a702996028f64fa
Reviewed-on: https://chromium-review.googlesource.com/c/1257899
Commit-Queue: Joel Einbinder <einbinder@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596443}

third_party/WebKit/LayoutTests/http/tests/devtools/elements/edit/set-outer-html-2-expected.txt

@@ -28,8 +28,8 @@ Bringing things back
 Wrapper identity: identity
 Event Symbol(AttrRemoved): H2
 Event Symbol(AttrRemoved): H2
-Event Symbol(CharacterDataModified): #text
 Event Symbol(NodeInserted): LI
+Event Symbol(NodeRemoved): #text
 ==========8<==========
 <div id="container" style="display:none">
       <p>WebKit is used by <a href="http://www.apple.com/safari/">Safari</a>, Dashboard, etc..</p>

third_party/WebKit/LayoutTests/http/tests/devtools/elements/edit/set-outer-html-whitespace-expected.txt

+Tests that DOMAgent.setOuterHTML can handle whitespace-only text nodes.
+
+Setting textContent to " "
+
+Setting textContent to "NOT_WHITESPACE"
+Event Symbol(NodeInserted): #text
+
+Setting textContent to "OTHER_NOT_WHITESPACE"
+Event Symbol(CharacterDataModified): #text
+
+Setting textContent to "   "
+Event Symbol(NodeRemoved): #text
+
+Setting textContent to ""
+
+

third_party/WebKit/LayoutTests/http/tests/devtools/elements/edit/set-outer-html-whitespace.js

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+(async function() {
+  TestRunner.addResult(`Tests that DOMAgent.setOuterHTML can handle whitespace-only text nodes.\n`);
+  await TestRunner.loadModule('elements_test_runner');
+  await TestRunner.showPanel('elements');
+  await TestRunner.loadHTML(`
+      <div id="container" style="display:none">
+        <child id="identity"></child>
+      </div>
+    `);
+  await TestRunner.evaluateInPagePromise(`
+      document.getElementById("identity").wrapperIdentity = "identity";
+  `);
+
+  async function setChildTextContent(textContent) {
+    var text = ElementsTestRunner.containerText.replace(/<child id="identity">.*<\/child>/, `<child id="identity">${textContent}</child>`);
+    TestRunner.addResult(`Setting textContent to "${textContent}"`)
+    await TestRunner.DOMAgent.setOuterHTML(ElementsTestRunner.containerId, text);
+    dumpEvents();
+  }
+
+  function dumpEvents() {
+    ElementsTestRunner.events.sort();
+
+    for (let i = 0; i < ElementsTestRunner.events.length; ++i)
+      TestRunner.addResult(ElementsTestRunner.events[i]);
+
+    ElementsTestRunner.events = [];
+    TestRunner.addResult("");
+  }
+
+  await new Promise(x => ElementsTestRunner.setUpTestSuite(x));
+  await setChildTextContent(' ')
+  await setChildTextContent('NOT_WHITESPACE')
+  await setChildTextContent('OTHER_NOT_WHITESPACE')
+  await setChildTextContent('   ')
+  await setChildTextContent('')
+  TestRunner.completeTest();
+})();

third_party/WebKit/LayoutTests/http/tests/devtools/elements/highlight/highlight-dom-updates-expected.txt

@@ -46,7 +46,6 @@ Running: testSetTextContentWithEmptyText
 
 Running: testClearTextNodeTextContent
 //*[@id="textTest"]
-//*[@id="textTest"]/text() ""
 
 Running: testAppendChildWhenHidden
 <No highlights>

third_party/blink/renderer/core/inspector/inspector_dom_agent.cc

@@ -1872,7 +1872,10 @@ void InspectorDOMAgent::DidInsertDOMNode(Node* node) {
 void InspectorDOMAgent::WillRemoveDOMNode(Node* node) {
   if (IsWhitespace(node))
     return;
+  DOMNodeRemoved(node);
+}
 
+void InspectorDOMAgent::DOMNodeRemoved(Node* node) {
   ContainerNode* parent = node->parentNode();
 
   // If parent is not mapped yet -> ignore the event.
@@ -1950,6 +1953,10 @@ void InspectorDOMAgent::StyleAttributeInvalidated(
 }
 
 void InspectorDOMAgent::CharacterDataModified(CharacterData* character_data) {
+  if (IsWhitespace(character_data)) {
+    DOMNodeRemoved(character_data);
+    return;
+  }
   int id = document_node_to_id_map_->at(character_data);
   if (!id) {
     // Push text node if it is being created.

third_party/blink/renderer/core/inspector/inspector_dom_agent.h

@@ -299,6 +299,7 @@ class CORE_EXPORT InspectorDOMAgent final
   void PushChildNodesToFrontend(int node_id,
                                 int depth = 1,
                                 bool traverse_frames = false);
+  void DOMNodeRemoved(Node*);
 
   void InvalidateFrameOwnerElement(HTMLFrameOwnerElement*);