Add cache to the travis build

Attempt to cache v8's git repo in order to shorten the build time.

Author: ignisf

.travis.yml

@@ -44,6 +44,10 @@ deploy:
   on:
     tags: true
     condition: $TRAVIS_OS_NAME = osx
+cache:
+  bundler: true
+  directories:
+    - vendor/v8/.git
 notifications:
   recipients:
     - cowboyd@thefrontside.net

ext/libv8/builder.rb

@@ -107,7 +107,7 @@ def setup_build_deps!
         end
         Dir.chdir('v8') do
           system "git checkout Makefile" # Work around a weird bug on FreeBSD
-          unless system "git checkout #{source_version}"
+          unless system "git checkout #{source_version} -- ."
             fail "unable to checkout source for v8 #{source_version}"
           end
           system "gclient sync" or fail "could not sync v8 build dependencies"