Bug 1390053 - Enable editor/libeditor/tests/test_bug830600.html on mochitest-e10s. r=masayuki

This test is turned off by bug 1269209 on e10s.  But there is no exactly reason why this test on e10s is turned off.

Although I run this test on e10s now, it seems to pass this.  So we should turn on this test even if e10s.

MozReview-Commit-ID: JHQP2ZYvsHL

--HG--
extra : rebase_source : 2bc45f0d2b5cc99bad93267f40191866264af414

editor/libeditor/tests/mochitest.ini

@@ -181,7 +181,6 @@ subsuite = clipboard
 [test_bug796839.html]
 [test_bug830600.html]
 subsuite = clipboard
-skip-if = e10s
 [test_bug832025.html]
 [test_bug850043.html]
 [test_bug857487.html]