CTTE: RenderImageResourceStyleImage always has a StyleImage.
<https://webkit.org/b/123390>

Codify the fact that RenderImageResourceStyleImage always wraps an
existing StyleImage object.

Reviewed by Antti Koivisto.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@158090 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/WebCore/rendering/RenderImageResourceStyleImage.cpp b/Source/WebCore/rendering/RenderImageResourceStyleImage.cpp
index e5052f1..b050fa8 100644
--- a/Source/WebCore/rendering/RenderImageResourceStyleImage.cpp
+++ b/Source/WebCore/rendering/RenderImageResourceStyleImage.cpp
@@ -34,10 +34,9 @@
 
 namespace WebCore {
 
-RenderImageResourceStyleImage::RenderImageResourceStyleImage(StyleImage* styleImage)
+RenderImageResourceStyleImage::RenderImageResourceStyleImage(StyleImage& styleImage)
     : m_styleImage(styleImage)
 {
-    ASSERT(m_styleImage);
 }
 
 RenderImageResourceStyleImage::~RenderImageResourceStyleImage()
@@ -49,7 +48,7 @@
     RenderImageResource::initialize(renderer);
 
     if (m_styleImage->isCachedImage())
-        m_cachedImage = static_cast<StyleCachedImage*>(m_styleImage.get())->cachedImage();
+        m_cachedImage = m_styleImage.get().cachedImage();
 
     m_styleImage->addClient(m_renderer);
 }