[Reland] Invalidate whitespace text on text color changes

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1704 matching lines @@
             diff.setNeedsPaintInvalidationLayer();
     }
 
     // If backdrop filter changed, and the layer does not paint into its own separate backing or it paints with filters, then we need to invalidate paints.
     if (diff.backdropFilterChanged() && hasLayer()) {
         DeprecatedPaintLayer* layer = toLayoutBoxModelObject(this)->layer();
         if (!layer->hasStyleDeterminedDirectCompositingReasons() || layer->paintsWithBackdropFilters())
             diff.setNeedsPaintInvalidationLayer();
     }
 
-    if (diff.textOrColorChanged() && !diff.needsPaintInvalidation()) {
+    // Optimization: for decoration/color property changes, invalidation is only needed if we have style or text affected by these properties.
+    if (diff.textDecorationOrColorChanged() && !diff.needsPaintInvalidation()) {
         if (style()->hasBorder() || style()->hasOutline()
             || style()->isBackgroundColorCurrentColor()
-            || (isText() && !toLayoutText(this)->isAllCollapsibleWhitespace()))
+            // Skip any text nodes that do not contain text boxes. Whitespace cannot be
+            // skipped or we will miss invalidating decorations (e.g., underlines).
+            || (isText() && !isBR() && toLayoutText(this)->hasTextBoxes()))
             diff.setNeedsPaintInvalidationObject();
     }
 
     // The answer to layerTypeRequired() for plugins, iframes, and canvas can change without the actual
     // style changing, since it depends on whether we decide to composite these elements. When the
     // layer status of one of these elements changes, we need to force a layout.
     if (!diff.needsFullLayout() && style() && isBoxModelObject()) {
         bool requiresLayer = toLayoutBoxModelObject(this)->layerTypeRequired() != NoDeprecatedPaintLayer;
         if (hasLayer() != requiresLayer)
             diff.setNeedsFullLayout();
@@ skipping 1652 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         fprintf(stderr, "Cannot showLayoutTree. Root is (nil)\n");
     }
 }
 
 #endif