Rebaseline shadertext2_{gpu,8888} after SkPaint::measureText changes

Rebaseline shadertext2_{gpu,8888} after SkPaint::measureText changes

These two GMs were missing from https://codereview.chromium.org/347393002/.

This CL is to fix http://108.170.220.121:10117/static/view.html#/view.html?resultsToLoad=%2Fresults%2Ffailures&displayLimitPending=50&showThumbnailsPending&mergeIdenticalRowsPending&imageSizePending=100&sortColumnSubdict=differenceData&sortColumnKey=perceptualDifference&hiddenResultTypes=failure-ignored,no-comparison,succeeded&hiddenConfigs=&builder=Test-Win7-ShuttleA-HD2000-x86-Release&test=

BUG=skia:
R=kkinnunen@nvidia.com, jvanverth@google.com, mtklein@google.com

Author: rmistry@google.com

Review URL: https://codereview.chromium.org/333193003