Make Blink test targets generally visible.
Make Blink test targets generally visible.

This makes heap_unittests, platform_unittests and wtf_unittests targets
public, so we can refer to them outside of Blink, in Chromium's root
BUILD.gn file.

Tested with the following command line:

$ gn gen ../../out_gn/Debug
$ ninja -C ../../out_gn/Debug all_blink

With the following diff in Chromium's BUILD.gn to test the new behavior.
+group("gn_all") {
+  # This should not be linked into production and depends on test targets.
+  testonly = true
+
+  deps = [
+    "//third_party/WebKit/public:blink_tests",
+  ]
+}

BUG=None
TEST=see above
R=dpranke@chromium.org
TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/910973002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@189894 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Bysmyyr/blink-crosswalk,smishenk/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,XiaosongWei/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk,Bysmyyr/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,Bysmyyr/blink-crosswalk,XiaosongWei/blink-crosswalk,PeterWangIntel/blink-crosswalk,kurli/blink-crosswalk,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,smishenk/blink-crosswalk,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,kurli/blink-crosswalk,smishenk/blink-crosswalk,smishenk/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,kurli/blink-crosswalk,XiaosongWei/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,kurli/blink-crosswalk,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,PeterWangIntel/blink-crosswalk,Bysmyyr/blink-crosswalk,Pluto-tv/blink-crosswalk,Bysmyyr/blink-crosswalk,smishenk/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,PeterWangIntel/blink-crosswalk,Bysmyyr/blink-crosswalk,PeterWangIntel/blink-crosswalk,PeterWangIntel/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,XiaosongWei/blink-crosswalk,PeterWangIntel/blink-crosswalk,Bysmyyr/blink-crosswalk,XiaosongWei/blink-crosswalk