[editing] Make DeleteInsignificantText() to handle spaces causing lin…

…e break

This patch changes `CompositeEditCommand::DeleteInsignificantText()`
not to remove `Text` node causing line break.

`Text` node causes line break should be significant because it can be
rendered when it doesn't cause line break afer changing something
around it.

Bug: 1322746
Change-Id: I2ba431d7d8e3406d5cb2249b4bb36f2263434a5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3817426
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1034947}

third_party/blink/renderer/core/editing/commands/composite_edit_command.cc

@@ -831,6 +831,14 @@ void CompositeEditCommand::RebalanceWhitespace() {
     RebalanceWhitespaceAt(selection.End());
 }
 
+static bool IsInsignificantText(const LayoutText& layout_text) {
+  if (layout_text.HasInlineFragments())
+    return false;
+  // Spaces causing line break don't have `NGFragmentItem` but it has
+  // non-zero length. See http://crbug.com/1322746
+  return !layout_text.ResolvedTextLength();
+}
+
 void CompositeEditCommand::DeleteInsignificantText(Text* text_node,
                                                    unsigned start,
                                                    unsigned end) {
@@ -843,7 +851,7 @@ void CompositeEditCommand::DeleteInsignificantText(Text* text_node,
   if (!text_layout_object)
     return;
 
-  if (!text_layout_object->HasInlineFragments()) {
+  if (IsInsignificantText(*text_layout_object)) {
     // whole text node is empty
     // Removing a Text node won't dispatch synchronous events.
     RemoveNode(text_node, ASSERT_NO_EDITING_ABORT);

third_party/blink/renderer/core/editing/commands/typing_command_test.cc

@@ -22,6 +22,27 @@ namespace blink {
 
 class TypingCommandTest : public EditingTestBase {};
 
+// http://crbug.com/1322746
+TEST_F(TypingCommandTest, DeleteInsignificantText) {
+  InsertStyleElement(
+      "b { display: inline-block; width: 100px; }"
+      "div { width: 100px; }");
+  Selection().SetSelection(
+      SetSelectionTextToBody("<div contenteditable>"
+                             "|<b><pre></pre></b> <a>abc</a>"
+                             "</div>"),
+      SetSelectionOptions());
+  EditingState editing_state;
+  TypingCommand::ForwardDeleteKeyPressed(GetDocument(), &editing_state);
+  ASSERT_FALSE(editing_state.IsAborted());
+
+  EXPECT_EQ(
+      u8"<div contenteditable>"
+      "|\u00A0<a>abc</a>"
+      "</div>",
+      GetSelectionTextFromBody());
+}
+
 // This is a regression test for https://crbug.com/585048
 TEST_F(TypingCommandTest, insertLineBreakWithIllFormedHTML) {
   SetBodyContent("<div contenteditable></div>");