Ratchet back style changes that rebuild nav caches

Many style changes do not visibly affect the way
links are detected -- so limit the rebuild to
style changes that either move the size the style,
or changes that edit the style's display property.

Styles appearing or disappearing (i.e., one is 0)
is not treated as a style version change since
these events accompany dom edits which are detected
outside of this change.

bug:3181683
Change-Id: Ie62ef524a956fcd9298ce5878b632645a22e461a

1 files changed, 14 insertions, 1 deletions

diff --git a/WebCore/dom/Element.cpp b/WebCore/dom/Element.cpp
index a86f30a..be74487 100644
--- a/WebCore/dom/Element.cpp
+++ b/WebCore/dom/Element.cpp
@@ -947,6 +947,17 @@ bool Element::pseudoStyleCacheIsInvalid(const RenderStyle* currentStyle, RenderS
     return false;
 }
 
+#ifdef ANDROID_STYLE_VERSION
+static bool displayDiff(const RenderStyle* s1, const RenderStyle* s2)
+{
+    if (!s1 || !s2)
+        return false;
+    return s1->display() != s2->display()
+        || s1->left() != s2->left() || s1->top() != s2->top()
+        || s1->right() != s2->right() || s1->bottom() != s2->bottom();
+}
+#endif
+
 void Element::recalcStyle(StyleChange change)
 {
     // Ref currentStyle in case it would otherwise be deleted when setRenderStyle() is called.
@@ -962,7 +973,9 @@ void Element::recalcStyle(StyleChange change)
 
     if ((change > NoChange || needsStyleRecalc())) {
 #ifdef ANDROID_STYLE_VERSION
-        document()->incStyleVersion();
+        RefPtr<RenderStyle> newStyle = document()->styleSelector()->styleForElement(this);
+        if (displayDiff(currentStyle.get(), newStyle.get()))
+            document()->incStyleVersion();
 #endif
         if (hasRareData())
             rareData()->resetComputedStyle();