First JavaScript testing implementation.

First JavaScript testing implementation.

This is a plan for testing JS inside of pdf files under pdfium:

Communication of results will be done via app.alert(), rather than
console.println(), since the latter is not hooked up to any API
callbacks.

pdfium_test.cc is modified to be more careful about use of stdout/stderr,
so that only the app.alert() and the unsupported feature callback use
stdout.  Diffing stdout against ..._expected.txt files gives the result.

I added a /javascript directory to separate these from the embeddertest
resources.

The alert callback is backported from XFA.  This was an omission.

BUG=https://code.google.com/p/pdfium/issues/detail?id=62
R=jam@chromium.org, thestig@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/72feb27fc174c2139b642eb7390fffac608f6c87

[Tom Sepez, 2015-02-06 17:53:55]

tsepez@chromium.org changed reviewers:
+ jam@chromium.org, thestig@chromium.org

[Tom Sepez, 2015-02-06 17:56:11]

John, Lei, please review.  Next step in my plan.

[Lei Zhang, 2015-02-06 22:53:07]

lgtm

https://codereview.chromium.org/872103003/diff/1/samples/pdfium_test.cc
File samples/pdfium_test.cc (right):

https://codereview.chromium.org/872103003/diff/1/samples/pdfium_test.cc#newco...
samples/pdfium_test.cc:227: (wchar_t*)malloc((characters + 1) *
sizeof(wchar_t));
avoid C style casting?

[jam, 2015-02-06 23:56:30]

lgtm

[Tom Sepez, 2015-02-06 23:58:44]

Committed patchset #1 (id:1) manually as
72feb27fc174c2139b642eb7390fffac608f6c87 (presubmit successful).