Make RenderObject::style() return a const object

Source/core/html/forms/InputType.cpp

Index: Source/core/html/forms/InputType.cpp
diff --git a/Source/core/html/forms/InputType.cpp b/Source/core/html/forms/InputType.cpp
index 650e9a695a8de9391f3bb0a744117e69aaeacc14..9129912df4f2394619c541acace6ec8150b61f41 100644
--- a/Source/core/html/forms/InputType.cpp
+++ b/Source/core/html/forms/InputType.cpp
@@ -592,7 +592,7 @@ String InputType::sanitizeValue(const String& proposedValue) const
 void InputType::warnIfValueIsInvalidAndElementIsVisible(const String& value) const
 {
     // Don't warn if the value is set in Modernizr.
-    LayoutStyle* style = element().layoutStyle();
+    const LayoutStyle* style = element().layoutStyle();
     if (style && style->visibility() != HIDDEN)
         warnIfValueIsInvalid(value);
 }
@@ -897,7 +897,7 @@ void InputType::stepUpFromRenderer(int n)
 
 void InputType::countUsageIfVisible(UseCounter::Feature feature) const
 {
-    if (LayoutStyle* style = element().layoutStyle()) {
+    if (const LayoutStyle* style = element().layoutStyle()) {
         if (style->visibility() != HIDDEN)
             UseCounter::count(element().document(), feature);
     }