[js-perf-test] fixup error in JSTests.json

BUG=
LOG=N
NOTRY=true
R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/1777873003

Cr-Commit-Position: refs/heads/master@{#34611}

test/js-perf-test/JSTests.json

@@ -108,7 +108,7 @@
     },
     {
       "name": "Object",
-      "path": ["."],
+      "path": ["Object"],
       "main": "run.js",
       "flags": ["--harmony"],
       "resources": [