Skip overflow adjustment checks when possible in StyleAdjuster

Source/core/css/resolver/StyleAdjuster.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 213 matching lines @@
         || style->hasTransformRelatedProperty()
         || style->hasMask()
         || style->clipPath()
         || style->boxReflect()
         || style->hasFilter()
         || style->hasBlendMode()
         || style->hasIsolation()
         || style->position() == StickyPosition
         || style->position() == FixedPosition
         || isInTopLayer(e, style)
-        || hasWillChangeThatCreatesStackingContext(style, e)
-        ))
+        || hasWillChangeThatCreatesStackingContext(style, e)))
         style->setZIndex(0);
 
     // will-change:transform should result in the same rendering behavior as having a transform,
     // including the creation of a containing block for fixed position descendants.
     if (!style->hasTransform() && style->willChangeProperties().contains(CSSPropertyWebkitTransform)) {
         bool makeIdentity = true;
         style->setTransform(TransformOperations(makeIdentity));
     }
 
     if (doesNotInheritTextDecoration(style, e))
         style->setTextDecorationsInEffect(style->textDecoration());
     else
         style->addToTextDecorationsInEffect(style->textDecoration());
 
-    // If either overflow value is not visible, change to auto.
-    if (style->overflowX() == OVISIBLE && style->overflowY() != OVISIBLE) {
-        // FIXME: Once we implement pagination controls, overflow-x should default to hidden
-        // if overflow-y is set to -webkit-paged-x or -webkit-page-y. For now, we'll let it
-        // default to auto so we can at least scroll through the pages.
-        style->setOverflowX(OAUTO);
-    } else if (style->overflowY() == OVISIBLE && style->overflowX() != OVISIBLE) {
-        style->setOverflowY(OAUTO);
-    }
-
-    // Table rows, sections and the table itself will support overflow:hidden and will ignore scroll/auto.
-    // FIXME: Eventually table sections will support auto and scroll.
-    if (style->display() == TABLE || style->display() == INLINE_TABLE
-        || style->display() == TABLE_ROW_GROUP || style->display() == TABLE_ROW) {
-        if (style->overflowX() != OVISIBLE && style->overflowX() != OHIDDEN)
-            style->setOverflowX(OVISIBLE);
-        if (style->overflowY() != OVISIBLE && style->overflowY() != OHIDDEN)
-            style->setOverflowY(OVISIBLE);
-    }
-
-    // Menulists should have visible overflow
-    if (style->appearance() == MenulistPart) {
-        style->setOverflowX(OVISIBLE);
-        style->setOverflowY(OVISIBLE);
-    }
+    if (style->overflowX() != OVISIBLE || style->overflowY() != OVISIBLE)
+        adjustOverflow(style, e);
 
     // Cull out any useless layers and also repeat patterns into additional layers.
     style->adjustBackgroundLayers();
     style->adjustMaskLayers();
 
     // Let the theme also have a crack at adjusting the style.
     if (style->hasAppearance())
         RenderTheme::theme().adjustStyle(style, e, m_cachedUAStyle);
 
     // If we have first-letter pseudo style, transitions, or animations, do not share this style.
     if (style->hasPseudoStyle(FIRST_LETTER) || style->transitions() || style->animations())
         style->setUnique();
 
     // FIXME: when dropping the -webkit prefix on transform-style, we should also have opacity < 1 cause flattening.
     if (style->preserves3D() && (style->overflowX() != OVISIBLE
         || style->overflowY() != OVISIBLE
         || style->hasFilter()))
         style->setTransformStyle3D(TransformStyle3DFlat);
 
     if (e && e->isSVGElement()) {
-        // Spec: http://www.w3.org/TR/SVG/masking.html#OverflowProperty
-        if (style->overflowY() == OSCROLL)
-            style->setOverflowY(OHIDDEN);
-        else if (style->overflowY() == OAUTO)
-            style->setOverflowY(OVISIBLE);
-
-        if (style->overflowX() == OSCROLL)
-            style->setOverflowX(OHIDDEN);
-        else if (style->overflowX() == OAUTO)
-            style->setOverflowX(OVISIBLE);
-
         // Only the root <svg> element in an SVG document fragment tree honors css position
         if (!(isSVGSVGElement(*e) && e->parentNode() && !e->parentNode()->isSVGElement()))
             style->setPosition(RenderStyle::initialPosition());
 
         // RenderSVGRoot handles zooming for the whole SVG subtree, so foreignObject content should
         // not be scaled again.
         if (isSVGForeignObjectElement(*e))
             style->setEffectiveZoom(RenderStyle::initialZoom());
 
         // SVG text layout code expects us to be a block-level style element.
@@ skipping 80 matching lines @@
         // since the theme will alter fonts and heights/widths.
         //
         // Don't apply intrinsic margins to image buttons. The designer knows how big the images are,
         // so we have to treat all image buttons as though they were explicitly sized.
         if (style->fontSize() >= 11 && (!isHTMLInputElement(element) || !toHTMLInputElement(element).isImageButton()))
             addIntrinsicMargins(style);
         return;
     }
 }
 
+void StyleAdjuster::adjustOverflow(RenderStyle* style, Element* element)
+{
+    ASSERT(style->overflowX() != OVISIBLE || style->overflowY() != OVISIBLE);
+
+    // If either overflow value is not visible, change to auto.
+    if (style->overflowX() == OVISIBLE && style->overflowY() != OVISIBLE) {
+        // FIXME: Once we implement pagination controls, overflow-x should default to hidden
+        // if overflow-y is set to -webkit-paged-x or -webkit-page-y. For now, we'll let it
+        // default to auto so we can at least scroll through the pages.
+        style->setOverflowX(OAUTO);
+    } else if (style->overflowY() == OVISIBLE && style->overflowX() != OVISIBLE) {
+        style->setOverflowY(OAUTO);
+    }
+
+    // Table rows, sections and the table itself will support overflow:hidden and will ignore scroll/auto.
+    // FIXME: Eventually table sections will support auto and scroll.
+    if (style->display() == TABLE || style->display() == INLINE_TABLE
+        || style->display() == TABLE_ROW_GROUP || style->display() == TABLE_ROW) {
+        if (style->overflowX() != OVISIBLE && style->overflowX() != OHIDDEN)
+            style->setOverflowX(OVISIBLE);
+        if (style->overflowY() != OVISIBLE && style->overflowY() != OHIDDEN)
+            style->setOverflowY(OVISIBLE);
+    }
+
+    // Menulists should have visible overflow
+    if (style->appearance() == MenulistPart) {
+        style->setOverflowX(OVISIBLE);
+        style->setOverflowY(OVISIBLE);
+    }
+
+    // Spec: http://www.w3.org/TR/SVG/masking.html#OverflowProperty
+    if (element && element->isSVGElement()) {
+        if (style->overflowY() == OSCROLL)
+            style->setOverflowY(OHIDDEN);
+        else if (style->overflowY() == OAUTO)
+            style->setOverflowY(OVISIBLE);
+
+        if (style->overflowX() == OSCROLL)
+            style->setOverflowX(OHIDDEN);
+        else if (style->overflowX() == OAUTO)
+            style->setOverflowX(OVISIBLE);
+    }
+}
+
 void StyleAdjuster::adjustStyleForDisplay(RenderStyle* style, RenderStyle* parentStyle)
 {
     if (style->display() == BLOCK && !style->isFloating())
         return;
 
     // FIXME: Don't support this mutation for pseudo styles like first-letter or first-line, since it's not completely
     // clear how that should work.
     if (style->display() == INLINE && style->styleType() == NOPSEUDO && style->writingMode() != parentStyle->writingMode())
         style->setDisplay(INLINE_BLOCK);
 
@@ skipping 24 matching lines @@
     if (style->writingMode() != TopToBottomWritingMode && (style->display() == BOX || style->display() == INLINE_BOX))
         style->setWritingMode(TopToBottomWritingMode);
 
     if (isDisplayFlexibleBox(parentStyle->display()) || isDisplayGridBox(parentStyle->display())) {
         style->setFloating(NoFloat);
         style->setDisplay(equivalentBlockDisplay(style->display(), style->isFloating(), !m_useQuirksModeStyles));
     }
 }
 
 }