Enable experimental support for sub-pixel font scaling

Source/core/rendering/LineWidth.h

Index: Source/core/rendering/LineWidth.h
diff --git a/Source/core/rendering/LineWidth.h b/Source/core/rendering/LineWidth.h
index 84b4ec58a5c3e6318bfd7230162ccbfc35c1066f..59e1442445e5f3dffad1c6b8d4fc7dc9a0b02301 100644
--- a/Source/core/rendering/LineWidth.h
+++ b/Source/core/rendering/LineWidth.h
@@ -48,8 +48,8 @@ class LineWidth {
 public:
     LineWidth(RenderBlockFlow&, bool isFirstLine, IndentTextOrNot shouldIndentText);
 
-    bool fitsOnLine() const { return currentWidth() <= m_availableWidth; }
-    bool fitsOnLine(float extra) const { return currentWidth() + extra <= m_availableWidth; }
+    bool fitsOnLine() const { return currentWidth() <= (m_availableWidth + LayoutUnit::epsilon()); }
+    bool fitsOnLine(float extra) const { return currentWidth() + extra <= (m_availableWidth + LayoutUnit::epsilon()); }
 
     float currentWidth() const { return m_committedWidth + m_uncommittedWidth; }
     // FIXME: We should eventually replace these three functions by ones that work on a higher abstraction.