Do not crash if SpellcheckWordIterator fails to initialize.
Do not crash if SpellcheckWordIterator fails to initialize.

SpellcheckWordIterator::Initialize may fail in low memory conditions.
We are seeing a lot of crashes where SpellcheckWordIterator::SetText
fails with null iterator.

Also see: http://codereview.chromium.org/7780030

BUG=
TEST=


Review URL: http://codereview.chromium.org/8994007

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@115080 0039d316-1c4b-4281-b951-d872f2087c98

ropik/chromium,yitian134/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,adobe/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,yitian134/chromium,adobe/chromium