Change first() and second() in CSSPairValue to return const references

Source/core/css/CSSValuePair.h

Index: Source/core/css/CSSValuePair.h
diff --git a/Source/core/css/CSSValuePair.h b/Source/core/css/CSSValuePair.h
index b429c66b4743620b3709d1dd127e99a3e31a049f..143332f4617c106901362f8d3ca347e138756534 100644
--- a/Source/core/css/CSSValuePair.h
+++ b/Source/core/css/CSSValuePair.h
@@ -47,8 +47,10 @@ public:
         return adoptRefWillBeNoop(new CSSValuePair(CSSPrimitiveValue::create(lengthSize.width(), style.effectiveZoom()), CSSPrimitiveValue::create(lengthSize.height(), style.effectiveZoom()), KeepIdenticalValues));
     }
 
-    CSSValue* first() const { return m_first.get(); }
-    CSSValue* second() const { return m_second.get(); }
+    CSSValue& first() { return *m_first; }
+    CSSValue& second() { return *m_second; }

[alancutter (OOO until 2018), 2015/08/31 05:49:21]

Can these be trivially removed? If they can be removed with further simple
patches please add a TODO.

[sashab, 2015/09/01 04:54:41]

It's not *super* easy to remove them... Lots of places don't use const
cssvalues, even though they probably should. But added a comment because you're
right, they shouldn't be here :)

+    const CSSValue& first() const { return *m_first; }
+    const CSSValue& second() const { return *m_second; }

[alancutter (OOO until 2018), 2015/08/31 05:49:21]

Now that these are references we should assert them in the constructor.

[sashab, 2015/09/01 04:54:41]

Thanks, done.

 
     String customCSSText() const
     {