Let FullscreenElementStack methods take references where possible

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index 06c26ccf261154257cc02fb924f532edbeeeddac..da33f26b5e37b125e42942e8c6ab43d2684a74a3 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -2666,12 +2666,12 @@ void Element::setFloatingPointAttribute(const QualifiedName& attributeName, doub
 
 void Element::webkitRequestFullscreen()
 {
-    FullscreenElementStack::from(document()).requestFullScreenForElement(this, ALLOW_KEYBOARD_INPUT, FullscreenElementStack::EnforceIFrameAllowFullScreenRequirement);
+    FullscreenElementStack::from(document()).requestFullScreenForElement(*this, ALLOW_KEYBOARD_INPUT, FullscreenElementStack::EnforceIFrameAllowFullScreenRequirement);
 }
 
 void Element::webkitRequestFullScreen(unsigned short flags)
 {
-    FullscreenElementStack::from(document()).requestFullScreenForElement(this, (flags | LEGACY_MOZILLA_REQUEST), FullscreenElementStack::EnforceIFrameAllowFullScreenRequirement);
+    FullscreenElementStack::from(document()).requestFullScreenForElement(*this, (flags | LEGACY_MOZILLA_REQUEST), FullscreenElementStack::EnforceIFrameAllowFullScreenRequirement);
 }
 
 void Element::setContainsFullScreenElement(bool flag)
@@ -3317,7 +3317,7 @@ bool Element::supportsStyleSharing() const
         || isHTMLAppletElement(*this)
         || isHTMLCanvasElement(*this))
         return false;
-    if (FullscreenElementStack::isActiveFullScreenElement(this))
+    if (FullscreenElementStack::isActiveFullScreenElement(*this))
         return false;
     return true;
 }