Start popular containers (Vector, Hash*) off with 1-element of storage under memory tool builds.

This might assist our ASAN + fuzzing efforts in hitting a couple of classes of bug:

1) Using a raw pointer into container storage, across a realloc().
2) Out-of-bounds reads based on pointer access (which would not necessarily get caught by our security asserts).

Review URL: https://chromiumcodereview.appspot.com/22548004

git-svn-id: svn://svn.chromium.org/blink/trunk@155703 bbb929c8-8fbe-4397-9dbb-9b2b20218538