Initializing Bidi status members of InlineFlowBox

Valgrind complained of use before initialization so initializing
InlineFlowBox's m_lineBreakBidiStatusEor, m_lineBreakBidiStatusLastStrong,
and m_lineBreakBidiStatusLast to LeftToRight.

BUG=368303

Review URL: https://codereview.chromium.org/252263002

git-svn-id: svn://svn.chromium.org/blink/trunk@173008 bbb929c8-8fbe-4397-9dbb-9b2b20218538