Implement FullScreen using top layer.

Source/web/FullscreenController.cpp

Index: Source/web/FullscreenController.cpp
diff --git a/Source/web/FullscreenController.cpp b/Source/web/FullscreenController.cpp
index 019c1d2e18be77f7baabaf7b55f91b3117a9926d..3a18d5021b795e1e110c1bf2bc768ad6f3d27a72 100644
--- a/Source/web/FullscreenController.cpp
+++ b/Source/web/FullscreenController.cpp
@@ -178,9 +178,10 @@ void FullscreenController::updateSize()
 
     updatePageScaleConstraints(false);
 
-    LayoutFullScreen* layoutObject = Fullscreen::from(*m_fullScreenFrame->document()).fullScreenLayoutObject();
-    if (layoutObject)
-        layoutObject->updateStyle();
+    Document* document = m_fullScreenFrame->document();
+    Element* fullscreenElement = Fullscreen::currentFullScreenElementFrom(*document);
+    if (fullscreenElement)
+        document->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::FullScreen));

[rune, 2015/09/22 11:47:56]

So, what is actually requiring a style recalc here?

It used to just recalculate the style for just the LayoutFullScreen, and since
it sets the width and height in px based on the viewport size, I understand why
it's necessary when changing the viewport size, but for all the other elements?

Couldn't you just use fullscreenElement->setNeedsStyleRecalc(LocalStyleChange,
...), to trigger the recalc + styleAdjustment (where the viewport px sizes are
now set)?

Also, if you implemented a method inside blink (Fullscreen for instance) that
looked up and did setNeeds..., you'd avoid the CORE_EXPORT on the FullScreen
constant. The setNeeds... calls for entering and exiting fullscreen are
contained in the Fullscreen class.

 }
 
 void FullscreenController::updatePageScaleConstraints(bool removeConstraints)