Update two layout tests to reflect bleeding in ctx.drawImage

With this skia change: https://codereview.chromium.org/2176193002/, canvas
drawImage() API call does bleeding, so these two layout tests needs to be
updated.

We need to rebase line fast/images/paint-subrect-grid.html, which is
marked as failure at this moment.

The test fast/canvas/DrawImageSinglePixelStretch.html has been re-written
to canvas-drawImage-bleed.html

BUG=355305

Review-Url: https://codereview.chromium.org/2186553003
Cr-Commit-Position: refs/heads/master@{#407959}
7 files changed