Make RenderObject::style() return a const object

Source/web/tests/WebDocumentTest.cpp

Index: Source/web/tests/WebDocumentTest.cpp
diff --git a/Source/web/tests/WebDocumentTest.cpp b/Source/web/tests/WebDocumentTest.cpp
index 2953bbe93a9e56974c3bb8301dc5ccda2a343012..ab15fa3c14c45b19a6b7a1281b8dfe89e5150607 100644
--- a/Source/web/tests/WebDocumentTest.cpp
+++ b/Source/web/tests/WebDocumentTest.cpp
@@ -41,7 +41,7 @@ TEST(WebDocumentTest, InsertStyleSheet)
     HTMLElement* bodyElement = coreDoc->body();
     ASSERT(bodyElement);
 
-    RenderStyle* style = bodyElement->renderStyle();
+    const RenderStyle* style = bodyElement->renderStyle();
     ASSERT(style);
 
     // Inserted stylesheet not yet applied.
@@ -73,13 +73,13 @@ TEST(WebDocumentTest, BeginExitTransition)
     Element* transitionElement = coreDoc->getElementById("foo");
     ASSERT(transitionElement);
 
-    RenderStyle* transitionStyle = transitionElement->renderStyle();
+    const RenderStyle* transitionStyle = transitionElement->renderStyle();
     ASSERT(transitionStyle);
 
     HTMLElement* bodyElement = coreDoc->body();
     ASSERT(bodyElement);
 
-    RenderStyle* bodyStyle = bodyElement->renderStyle();
+    const RenderStyle* bodyStyle = bodyElement->renderStyle();
     ASSERT(bodyStyle);
     // The transition_exit.css stylesheet should not have been applied at this point.
     ASSERT_EQ(Color(0, 0, 0), bodyStyle->visitedDependentColor(CSSPropertyColor));
@@ -118,13 +118,13 @@ TEST(WebDocumentTest, BeginExitTransitionToNativeApp)
     Element* transitionElement = coreDoc->getElementById("foo");
     ASSERT(transitionElement);
 
-    RenderStyle* transitionStyle = transitionElement->renderStyle();
+    const RenderStyle* transitionStyle = transitionElement->renderStyle();
     ASSERT(transitionStyle);
 
     HTMLElement* bodyElement = coreDoc->body();
     ASSERT(bodyElement);
 
-    RenderStyle* bodyStyle = bodyElement->renderStyle();
+    const RenderStyle* bodyStyle = bodyElement->renderStyle();
     ASSERT(bodyStyle);
     // The transition_exit.css stylesheet should not have been applied at this point.
     ASSERT_EQ(Color(0, 0, 0), bodyStyle->visitedDependentColor(CSSPropertyColor));
@@ -161,7 +161,7 @@ TEST(WebDocumentTest, HideAndShowTransitionElements)
     Element* transitionElement = coreDoc->getElementById("foo");
     ASSERT(transitionElement);
 
-    RenderStyle* transitionStyle = transitionElement->renderStyle();
+    const RenderStyle* transitionStyle = transitionElement->renderStyle();
     ASSERT(transitionStyle);
     EXPECT_EQ(transitionStyle->opacity(), 1);