Refactor some first-letter handling code in TextIterator
This patch reorganizes code in TextIterator as a preparation to reduce
the level of hackiness in the class. The patch consists of:
1. Introduction of helper functions to reduce code duplication
2. Delay definition of |run_start| in HandleTextBox()
3. Changing some variable types of |const unsigned|
A follow-up patch will reduce the hackiness: crrev.com/2883163002
BUG=721957
TEST=n/a; no behavioral changes
Review-Url: https://codereview.chromium.org/2888463002
Cr-Commit-Position: refs/heads/master@{#472031}
2 files changed
