wordBreakIterator shouldn't require bloatedCharacters

This CL teaches wordBreakIterator to use ICU's UText data structure to present
the source text for wordBreakIterator in Latin-1. That lets us avoid calling
bloatedCharacters when we need a wordBreakIterator.

R=eseidel@chromium.org
BUG=254708

Review URL: https://codereview.chromium.org/18967009

git-svn-id: svn://svn.chromium.org/blink/trunk@154152 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Added test for CustomEvent init SerializedScriptValue assert. This is a simple test of the initCustomEvent internal API to make sure that it can be called, and that after initialization, the detail getter can be successfully used.

NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/18965006

git-svn-id: svn://svn.chromium.org/blink/trunk@154153 bbb929c8-8fbe-4397-9dbb-9b2b20218538