[ios] Adds the HttpServer to the ios_web_shell_eg2test runner app.

EG2 tests can now interact directly with the in-process HttpServer. The
resulting URLs can be sent over to the EG2 app process, which will be
able to load pages even if they are hosted by a server in another
process.  The WebShellTestCase fixture is modified to compile under both
EG1 and EG2 and used to set up and tear down the HttpServer.

BUG=930859

Change-Id: Ie56274bef53687ef8ac90058954f2daefed5f351
Reviewed-on: https://chromium-review.googlesource.com/c/1479927
Reviewed-by: Justin Cohen <[email protected]>
Commit-Queue: Rohit Rao <[email protected]>
Cr-Commit-Position: refs/heads/master@{#634171}
4 files changed