Move RenderTextInfo and WordMeasurement into their own headers.

Source/core/rendering/line/LineBreaker.h

Index: Source/core/rendering/line/LineBreaker.h
diff --git a/Source/core/rendering/line/LineBreaker.h b/Source/core/rendering/line/LineBreaker.h
index 5726589c71d396daf8d69af7711d20947e7cc971..2cb519205dfa52a2aaf769e3ac1ccf4d9e7fdc8e 100644
--- a/Source/core/rendering/line/LineBreaker.h
+++ b/Source/core/rendering/line/LineBreaker.h
@@ -25,23 +25,13 @@
 
 #include "core/rendering/InlineIterator.h"
 #include "core/rendering/line/LineInfo.h"
-#include "platform/text/TextBreakIterator.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
 enum WhitespacePosition { LeadingWhitespace, TrailingWhitespace };
 
-class RenderText;
-
-struct RenderTextInfo {
-    RenderTextInfo();
-    ~RenderTextInfo();
-
-    RenderText* m_text;
-    LazyLineBreakIterator m_lineBreakIterator;
-    const Font* m_font;
-};
+struct RenderTextInfo;
 
 class LineBreaker {
 public: