Reviewed by Eric Seidel.

        Add functions to update left and right offsets to LineOffsets
        https://bugs.webkit.org/show_bug.cgi?id=58028

        Added update() and shrinkWidthForNewFloatIfNeeded(FloatingObject*) to LineOffsets,
        which are used to update m_left and m_right. Also added m_block and m_isFirstLine
        member variables to LineOffsets so that users of LineOffsets don't have to pass them around.

        * rendering/RenderBlock.h:
        * rendering/RenderBlockLineLayout.cpp:
        (WebCore::RenderBlock::skipLeadingWhitespace): No longer passes firstLine to positionNewFloatOnLine.
        (WebCore::LineOffsets::LineOffsets): Takes RenderBlock* and isFirstLine instead of left and right offsets.
        (WebCore::LineOffsets::update): Extracted from findNextLineBreak and positionNewFloatOnLine.
        (WebCore::LineOffsets::shrinkWidthForNewFloatIfNeeded): Extracted from positionNewFloatOnLine.
        (WebCore::RenderBlock::findNextLineBreak): Calls skipLeadingWhitespace and positionNewFloatOnLine.
        (WebCore::RenderBlock::positionNewFloatOnLine): Calls shrinkWidthForNewFloatIfNeeded and update and
        no longer passes firstLine around.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@83165 268f45cc-cd09-0410-ab3c-d52691b4dbfc