Unittests don't use deprecated APIs. Yay!

Make sure it stays that way

BUG=v8:4134
R=yangguo@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/1242563003

Cr-Commit-Position: refs/heads/master@{#29741}

test/unittests/unittests.gyp

@@ -22,6 +22,10 @@
       'include_dirs': [
         '../..',
       ],
+      'defines': [
+        # TODO(jochen): Remove again after this is globally turned on.
+        'V8_IMMINENT_DEPRECATION_WARNINGS',
+      ],
       'sources': [  ### gcmole(all) ###
         'base/bits-unittest.cc',
         'base/cpu-unittest.cc',