[test] Make msan work for v8 stand-alone.

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index 8deb181210873309d86d778a1fecf2b6da9f1eeb..166e59f4331840073d9a446aaf1b37c13de3286d 100644
--- a/DEPS
+++ b/DEPS
@@ -17,6 +17,10 @@ deps = {
     Var("git_url") + "/external/googletest.git" + "@" + "8245545b6dc9c4703e6496d1efd19e975ad2b038",  # from svn revision 700
   "v8/testing/gmock":
     Var("git_url") + "/external/googlemock.git" + "@" + "29763965ab52f24565299976b936d1265cb6a271",  # from svn revision 501
+  "v8/third_party/libc++/trunk":
+     Var("git_url") + "/chromium/llvm-project/libcxx.git" + "@" + "48198f9110397fff47fe7c37cbfa296be7d44d3d",
+  "v8/third_party/libc++abi/trunk":
+     Var("git_url") + "/chromium/llvm-project/libcxxabi.git" + "@" + "4ad1009ab3a59fa7a6896d74d5e4de5885697f95",
   "v8/tools/clang":
     Var("git_url") + "/chromium/src/tools/clang.git" + "@" + "90fb65e7a9a5c9d6d9613dfb0e78921c52ca9cfc",
 }