The default is 64kb buffer, not 4kb.

Closes GH-702.

Closes GH-194.
Closes GH-701.

Closes GH-160.

Closes GH-715, GH-716.

When adding a listener for a signal event, removing it, and
adding it back again, it triggers a condition with an
undefined variable.

Closes GH-677.

Closes GH-694.

In attempt to understand buildbot failures.

We need to clear out and re-create the tmp directory when running
valgrind just like for the normal test run.

Closes GH-686.

Closes GH-684.

Closes GH-680.

For GH-680.

BUG=v8:884

Use 'openssl sha1' instead of 'shasum'