Adding derived sources for platform.

Pending moves from core/platform to platform have a dependency on
derived sources. Add support in this changelist.

R=abarth@chromium.org, abarth, eseidel
BUG=297477

Review URL: https://codereview.chromium.org/26697002

git-svn-id: svn://svn.chromium.org/blink/trunk@159354 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Update TestExpectations to match the bots.

TBR=toyoshim@chromium.org

Review URL: https://codereview.chromium.org/26846004

git-svn-id: svn://svn.chromium.org/blink/trunk@159355 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert r158912 due to tcmalloc corruption.

This also reverts r159311, which fixed a use-after-free introduced in
r158912.

BUG=305884,305080,301514
R=abarth@chromium.org, jochen@chromium.org

Review URL: https://codereview.chromium.org/26763003

git-svn-id: svn://svn.chromium.org/blink/trunk@159356 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add another flaky test line.

TBR=toyoshim@chromium.org

Review URL: https://codereview.chromium.org/26900003

git-svn-id: svn://svn.chromium.org/blink/trunk@159357 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix a performance issue in nextBoundary and previousBoundary

When iterating through DOM nodes nextBoundary and previousBoundary
convert the contents of nodes using text security to a sequence of 'x'
characters. The SimplifiedBackwardsTextIterator and TextIterator may
iterate past node boundaries. Before this patch, the transformation was
done looking at the starting node rather than the current node. In some
situations, this replaced all boundaries with 'x' and caused the
iterator to continue iterating and transforming until the extent of the
document.

BUG=121918

Review URL: https://codereview.chromium.org/26626003

git-svn-id: svn://svn.chromium.org/blink/trunk@159358 bbb929c8-8fbe-4397-9dbb-9b2b20218538