Make RenderObject::style() return a const object

Source/core/layout/LayoutTextControl.cpp

Index: Source/core/layout/LayoutTextControl.cpp
diff --git a/Source/core/layout/LayoutTextControl.cpp b/Source/core/layout/LayoutTextControl.cpp
index aee7181a6e326c5b437001b2798eb881802cb842..fc2d7d7e12ec24dca9a0be204bb7ec62f4f2f7e4 100644
--- a/Source/core/layout/LayoutTextControl.cpp
+++ b/Source/core/layout/LayoutTextControl.cpp
@@ -72,8 +72,8 @@ void LayoutTextControl::styleDidChange(StyleDifference diff, const LayoutStyle*
     if (innerEditorRenderer) {
         // We may have set the width and the height in the old style in layout().
         // Reset them now to avoid getting a spurious layout hint.
-        innerEditorRenderer->style()->setHeight(Length());
-        innerEditorRenderer->style()->setWidth(Length());
+        innerEditorRenderer->mutableStyle()->setHeight(Length());
+        innerEditorRenderer->mutableStyle()->setWidth(Length());
         innerEditorRenderer->setStyle(createInnerEditorStyle(styleRef()));
         innerEditor->setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::Control));
     }