Fix unexpected erasing textQuad

third_party/WebKit/Source/core/layout/LayoutText.cpp

 /*
  * (C) 1999 Lars Knoll (knoll@kde.org)
  * (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 362 matching lines @@
   // coordinates are unsigneds, so changing this function to take ints causes
   // various internal mismatches. But selectionRect takes ints, and passing
   // UINT_MAX to it causes trouble. Ideally we'd change selectionRect to take
   // unsigneds, but that would cause many ripple effects, so for now we'll just
   // clamp our unsigned parameters to INT_MAX.
   ASSERT(end == UINT_MAX || end <= INT_MAX);
   ASSERT(start <= INT_MAX);
   start = std::min(start, static_cast<unsigned>(INT_MAX));
   end = std::min(end, static_cast<unsigned>(INT_MAX));
 
-  bool hasCheckedBoxInRange = false;
+  // This function is always called in sequence that this check should work.
+  bool hasCheckedBoxInRange = !rects.isEmpty();
 
   for (InlineTextBox* box = firstTextBox(); box; box = box->nextTextBox()) {
     // Note: box->end() returns the index of the last character, not the index
     // past it
     if (start <= box->start() && box->end() < end) {
       FloatRect r(box->frameRect());
       if (useSelectionHeight) {
         LayoutRect selectionRect = box->localSelectionRect(start, end);
         if (box->isHorizontal()) {
           r.setHeight(selectionRect.height().toFloat());
@@ skipping 102 matching lines @@
   end = std::min(end, static_cast<unsigned>(INT_MAX));
 
   const unsigned caretMinOffset = static_cast<unsigned>(this->caretMinOffset());
   const unsigned caretMaxOffset = static_cast<unsigned>(this->caretMaxOffset());
 
   // Narrows |start| and |end| into |caretMinOffset| and |careMaxOffset|
   // to ignore unrendered leading and trailing whitespaces.
   start = std::min(std::max(caretMinOffset, start), caretMaxOffset);
   end = std::min(std::max(caretMinOffset, end), caretMaxOffset);
 
-  bool hasCheckedBoxInRange = false;
+  // This function is always called in sequence that this check should work.
+  bool hasCheckedBoxInRange = !quads.isEmpty();
 
   for (InlineTextBox* box = firstTextBox(); box; box = box->nextTextBox()) {
     // Note: box->end() returns the index of the last character, not the index
     // past it
     if (start <= box->start() && box->end() < end) {
       LayoutRect r(box->frameRect());
       if (useSelectionHeight) {
         LayoutRect selectionRect = box->localSelectionRect(start, end);
         if (box->isHorizontal()) {
           r.setHeight(selectionRect.height());
@@ skipping 1573 matching lines @@
   LayoutRect rect = LayoutRect(
       IntRect(firstRunX(), firstRunY(), linesBox.width(), linesBox.height()));
   LayoutBlock* block = containingBlock();
   if (block && hasTextBoxes())
     block->adjustChildDebugRect(rect);
 
   return rect;
 }
 
 }  // namespace blink