AI 143540: Try not to start TextView lines with non-starter characters.

  TextView was previously following the "relaxed" line breaking
  convention and would allow a line break between any two
  ideographic characters.  Tighten that up and do not allow
  line breaks before non-starter characters (sound and iteration
  marks and small Hiragana and Katakana).
  BUG=1735619

Automated import of CL 143540