Enable compiling mjsunit tests as ES6 modules

Enable compiling mjsunit tests as ES6 modules

Adding the line "// MODULE" to an mjsunit file will now cause
run-tests.py to prefix the test case with "--module" in the
d8 commandline.

d8 has itself been updated to treat files preceded with "--module" as
modules (that is, it compiles them with ScriptCompiler::CompileModule,
and turns on --harmony-modules).

Committed: https://crrev.com/a18b797fd96730bc9407d27195fac66f44865004
Cr-Commit-Position: refs/heads/master@{#26555}

[adamk, 2015-02-06 21:59:05]

adamk@chromium.org changed reviewers:
+ rossberg@chromium.org

[adamk, 2015-02-06 21:59:05]

Not sure who the best reviewers are for the d8 and testcfg changes. CCed
machenbach and yangguo, as they've both touched nearby code relatively recently.

[adamk, 2015-02-09 19:29:34]

ping?

[rossberg, 2015-02-10 13:07:16]

lgtm

[adamk, 2015-02-10 17:40:53]

The CQ bit was checked by adamk@chromium.org

[commit-bot: I haz the power, 2015-02-10 17:41:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/902263002/1

[commit-bot: I haz the power, 2015-02-10 19:11:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-10 19:12:01]

Patchset 1 (id:??) landed as
https://crrev.com/a18b797fd96730bc9407d27195fac66f44865004
Cr-Commit-Position: refs/heads/master@{#26555}