Add some better documentation to LayoutObject

Source/core/layout/LayoutBox.h

Index: Source/core/layout/LayoutBox.h
diff --git a/Source/core/layout/LayoutBox.h b/Source/core/layout/LayoutBox.h
index 2a00d921812cd23eb2aae0a3d5b82a4fc1d588e9..d15741cc22abd0fdbf7cd9fd9539099297a47eea 100644
--- a/Source/core/layout/LayoutBox.h
+++ b/Source/core/layout/LayoutBox.h
@@ -849,9 +849,13 @@ private:
 
 protected:
     // The preferred logical width of the element if it were to break its lines at every possible opportunity.
+    // CSS 2.1 calls this width the 'preferred minimum width'.

[Julien - ping for review, 2015/08/27 18:56:54]

Added minimum content width to this that I missed. Also broke the text to have a
tighter paragraph.

+    // See https://drafts.csswg.org/css-sizing-3/#intrinsic for more information.
     LayoutUnit m_minPreferredLogicalWidth;
 
     // The preferred logical width of the element if it never breaks any lines at all.
+    // CSS 2.1 calls this width the 'preferred width'.

[Julien - ping for review, 2015/08/27 18:56:54]

Added "maximum cell width" to this that I missed.

+    // See https://drafts.csswg.org/css-sizing-3/#intrinsic for more information.
     LayoutUnit m_maxPreferredLogicalWidth;
 
     // Our overflow information.