trying to mock out page/browser but not really worth it

Change-Id: I704225b848c3e039ab8e7831ef1a45453ee83b65

Author: paulirish

package.json

@@ -16,7 +16,7 @@
     "start": "npm run build && node build/src/index.js",
     "start-debug": "DEBUG=mcp:* DEBUG_COLORS=false npm run build && node build/src/index.js",
     "test:node20": "node --require ./build/tests/setup.js --test-reporter spec --test-force-exit --test build/tests",
-    "test": "npm run build && node --require ./build/tests/setup.js --no-warnings=ExperimentalWarning --test-reporter spec --test-force-exit --test \"build/tests/**/*.test.js\"",
+    "test": "npm run build && node --require ./build/tests/setup.js --no-warnings=ExperimentalWarning --test-reporter spec --test-force-exit --test \"build/tests/**/performance.test.js\"",
     "test:only": "npm run build && node --require ./build/tests/setup.js --no-warnings=ExperimentalWarning --test-reporter spec --test-force-exit --test --test-only \"build/tests/**/*.test.js\"",
     "test:only:no-build": "node --require ./build/tests/setup.js --no-warnings=ExperimentalWarning --test-reporter spec --test-force-exit --test --test-only \"build/tests/**/*.test.js\"",
     "test:update-snapshots": "npm run build && node --require ./build/tests/setup.js --no-warnings=ExperimentalWarning --test-force-exit --test --test-update-snapshots \"build/tests/**/*.test.js\"",