Set up PATH to find DLLs for tests

python/servo/testing_commands.py

@@ -221,7 +221,11 @@ def test_unit(self, test_name=None, package=None):
         env["RUST_BACKTRACE"] = "1"
 
         if sys.platform in ("win32", "msys"):
-            if "msvc" not in host_triple():
+            if "msvc" in host_triple():
+                # on MSVC, we need some DLLs in the path. They were copied
+                # in to the servo.exe build dir, so just point PATH to that.
+                env["PATH"] = "%s%s%s" % (path.dirname(self.get_binary_path(False, False)), os.pathsep, env["PATH"])
+            else:
                 env["RUSTFLAGS"] = "-C link-args=-Wl,--subsystem,windows"
 
         result = call(args, env=env, cwd=self.servo_crate())