wash: Make it possible to exit wash

* Add an "X" button to the wash window titlebar.
* Make readline return null for Ctrl-D on an empty line.
* Make wash shell exit on null return value from readline.

Change-Id: I2c56f9be32f0456ed39ac9bb856da47b4c3f10d0
Reviewed-on: https://chromium-review.googlesource.com/198411
Reviewed-by: Robert Ginda <rginda@chromium.org>
Tested-by: Robert Ginda <rginda@chromium.org>
wam/wash: Add file-access flag to load_tests.sh/run_local.sh

Change-Id: If4c5d28eb2f44dfa905c6906e448de241e59e72a
Reviewed-on: https://chromium-review.googlesource.com/198397
Reviewed-by: Robert Ginda <rginda@chromium.org>
Tested-by: Robert Ginda <rginda@chromium.org>
Changes the iframe src from javascript to '#' in FF so it won't
violate the integrating app's Content Security Policy if they disable
inlining js.

Change-Id: I3a6f8962fd973e6535225c98171bb0379cc87b58
Reviewed-on: https://chromium-review.googlesource.com/198595
Reviewed-by: Robert Ginda <rginda@chromium.org>
Tested-by: Robert Ginda <rginda@chromium.org>
Bag o' fixes for wash and wam, in support of nassh.

wam:
* Add generic wam.FileSystem.Error.RuntimeError.
* Add binding.fs.dirName utility function.
* Plumb stdout/stderr acknowledgement for flow control.
* Add jsfs.Filesystem..makeEntry.
* wam.transport.ChromePort fixes.

wash:
* Fix 'delete-char' in readline.
* Re-organize paths into /apps/wash, /apps/chrome, etc.
* Fix double '//' when setting PWD from the cd command.
* export PWD='/' at startup.
* Wait for hterm to be ready before firing wash.TerminalWindow..onInit().

Change-Id: If1e400f6d1a691939ba4c9d3f99b4d88c3879258
Reviewed-on: https://chromium-review.googlesource.com/198613
Reviewed-by: Robert Ginda <rginda@chromium.org>
Tested-by: Robert Ginda <rginda@chromium.org>