Disable LCD text explicitly in SkPictureImageFilter::onFilterImage()

As an intermediate fix for
https://code.google.com/p/skia/issues/detail?id=3142, we can use a
non-public SkCanvas constructor and force-disable LCD text.

BUG=skia:3142
R=reed@google.com,senorblanco@google.com

Review URL: https://codereview.chromium.org/725243004