ci: run benchmarks before attempting to deploy them to github pages

The 'script' key in the deploy section that is supposed to run the
benchmarks isn't doing anything. Because of this, Travis bumps its head
when trying to deploy a non-existing directory to github pages, which
makes that our master branch is now consistently red.

This patch restores the setup that worked before.

This partially reverts commit aa66ef98ea.

.travis.yml

@@ -89,6 +89,13 @@ script:
   DENO_BUILD_MODE=release ./tools/test.py
 
 - sccache --stop-server
+after_success:
+- |
+  # Run benchmarks and publish the result to github pages.
+  if [ $BENCHMARK ]; then
+    ./tools/benchmark.py target/release &&
+    cp -r website/* gh-pages/
+  fi
 before_deploy:
 - gzip -c target/release/deno > target/release/deno_${TRAVIS_OS_NAME}_x64.gz
 deploy:
@@ -100,9 +107,7 @@ deploy:
     tags: true
     repo: denoland/deno
   skip-cleanup: true
-# Run benchmarks and publish the result to github pages.
 - provider: pages
-  script: ./tools/benchmark.py target/release && cp -r website/* gh-pages/
   github-token: *github-token
   keep-history: true
   local-dir: gh-pages