Move root element fixups to nsStyleContext so they happen before CalcDifference calls in style reresolution and we reframe less. b=245327 r+sr=bzbarsky

content/base/src/nsStyleContext.cpp

@@ -379,6 +379,26 @@ nsStyleContext::ApplyStyleFixups(nsIPresContext* aPresContext)
       uniqueText->mTextAlign = NS_STYLE_TEXT_ALIGN_DEFAULT;
     }
   }
+
+  // CSS2.1 section 9.2.4 specifies fixups for the 'display' property of
+  // the root element.  We can't implement them in nsRuleNode because we
+  // don't want to store all display structs that aren't 'block',
+  // 'inline', or 'table' in the style context tree on the off chance
+  // that the root element has its style reresolved later.  So do them
+  // here if needed, by changing the style data, so that other code
+  // doesn't get confused by looking at the style data.
+  if (!mParent) {
+    if (disp->mDisplay != NS_STYLE_DISPLAY_NONE &&
+        disp->mDisplay != NS_STYLE_DISPLAY_BLOCK &&
+        disp->mDisplay != NS_STYLE_DISPLAY_TABLE) {
+      nsStyleDisplay *mutable_display = NS_STATIC_CAST(nsStyleDisplay*,
+        GetUniqueStyleData(eStyleStruct_Display));
+      if (mutable_display->mDisplay == NS_STYLE_DISPLAY_INLINE_TABLE)
+        mutable_display->mDisplay = NS_STYLE_DISPLAY_TABLE;
+      else
+        mutable_display->mDisplay = NS_STYLE_DISPLAY_BLOCK;
+    }
+  }
 }
 
 void

layout/base/nsCSSFrameConstructor.cpp

@@ -3497,24 +3497,9 @@ nsCSSFrameConstructor::ConstructDocElementFrame(nsIPresShell*        aPresShell,
   PRBool isBlockFrame = PR_FALSE;
   nsresult rv;
 
-  // CSS2.1 section 9.2.4 specifies fixups for the 'display' property
-  // of the root element.  We can't implement them in nsRuleNode because
-  // it doesn't (and shouldn't, for nodes that can have siblings) know
-  // the content node.  So do them here if needed, by changing the style
-  // data, so that other code doesn't get confused by looking at the style
-  // data.
-  if (display->mDisplay != NS_STYLE_DISPLAY_NONE &&
-      display->mDisplay != NS_STYLE_DISPLAY_BLOCK &&
-      display->mDisplay != NS_STYLE_DISPLAY_TABLE) {
-    nsStyleDisplay *mutable_display = NS_STATIC_CAST(nsStyleDisplay*,
-      styleContext->GetUniqueStyleData(eStyleStruct_Display));
-    display = mutable_display;
-
-    if (mutable_display->mDisplay == NS_STYLE_DISPLAY_INLINE_TABLE)
-      mutable_display->mDisplay = NS_STYLE_DISPLAY_TABLE;
-    else
-      mutable_display->mDisplay = NS_STYLE_DISPLAY_BLOCK;
-  }
+  // The rules from CSS 2.1, section 9.2.4, have already been applied
+  // by the style system, so we can assume that display->mDisplay is
+  // either NONE, BLOCK, or TABLE.
 
   PRBool docElemIsTable = display->mDisplay == NS_STYLE_DISPLAY_TABLE;
 

layout/html/style/src/nsCSSFrameConstructor.cpp

@@ -3497,24 +3497,9 @@ nsCSSFrameConstructor::ConstructDocElementFrame(nsIPresShell*        aPresShell,
   PRBool isBlockFrame = PR_FALSE;
   nsresult rv;
 
-  // CSS2.1 section 9.2.4 specifies fixups for the 'display' property
-  // of the root element.  We can't implement them in nsRuleNode because
-  // it doesn't (and shouldn't, for nodes that can have siblings) know
-  // the content node.  So do them here if needed, by changing the style
-  // data, so that other code doesn't get confused by looking at the style
-  // data.
-  if (display->mDisplay != NS_STYLE_DISPLAY_NONE &&
-      display->mDisplay != NS_STYLE_DISPLAY_BLOCK &&
-      display->mDisplay != NS_STYLE_DISPLAY_TABLE) {
-    nsStyleDisplay *mutable_display = NS_STATIC_CAST(nsStyleDisplay*,
-      styleContext->GetUniqueStyleData(eStyleStruct_Display));
-    display = mutable_display;
-
-    if (mutable_display->mDisplay == NS_STYLE_DISPLAY_INLINE_TABLE)
-      mutable_display->mDisplay = NS_STYLE_DISPLAY_TABLE;
-    else
-      mutable_display->mDisplay = NS_STYLE_DISPLAY_BLOCK;
-  }
+  // The rules from CSS 2.1, section 9.2.4, have already been applied
+  // by the style system, so we can assume that display->mDisplay is
+  // either NONE, BLOCK, or TABLE.
 
   PRBool docElemIsTable = display->mDisplay == NS_STYLE_DISPLAY_TABLE;
 

layout/style/nsStyleContext.cpp

@@ -379,6 +379,26 @@ nsStyleContext::ApplyStyleFixups(nsIPresContext* aPresContext)
       uniqueText->mTextAlign = NS_STYLE_TEXT_ALIGN_DEFAULT;
     }
   }
+
+  // CSS2.1 section 9.2.4 specifies fixups for the 'display' property of
+  // the root element.  We can't implement them in nsRuleNode because we
+  // don't want to store all display structs that aren't 'block',
+  // 'inline', or 'table' in the style context tree on the off chance
+  // that the root element has its style reresolved later.  So do them
+  // here if needed, by changing the style data, so that other code
+  // doesn't get confused by looking at the style data.
+  if (!mParent) {
+    if (disp->mDisplay != NS_STYLE_DISPLAY_NONE &&
+        disp->mDisplay != NS_STYLE_DISPLAY_BLOCK &&
+        disp->mDisplay != NS_STYLE_DISPLAY_TABLE) {
+      nsStyleDisplay *mutable_display = NS_STATIC_CAST(nsStyleDisplay*,
+        GetUniqueStyleData(eStyleStruct_Display));
+      if (mutable_display->mDisplay == NS_STYLE_DISPLAY_INLINE_TABLE)
+        mutable_display->mDisplay = NS_STYLE_DISPLAY_TABLE;
+      else
+        mutable_display->mDisplay = NS_STYLE_DISPLAY_BLOCK;
+    }
+  }
 }
 
 void