Reviewed by Darin, landed by Maciej.

    Reviewed by Darin, landed by Maciej.

        * BuildSlaveSupport/build-launcher-app: Added.  Builds WebKit.app from WebKitLauncher
          and bundles the WebKit frameworks inside it.
        * BuildSlaveSupport/build-launcher-dmg: Added.  Builds, and optionally uploads, a disk image
          containing WebKit.app.
        * BuildSlaveSupport/run-performance-tests:  Use currentSVNRevision.
        * Scripts/webkitdirs.pm:  Add currentSVNRevision to retrieve the revision
          number of the SVN working copy.
        * WebKitLauncher: Added.
        * WebKitLauncher/Info.plist: Added.
        * WebKitLauncher/WebKitLauncher.xcodeproj: Added.
        * WebKitLauncher/WebKitLauncher.xcodeproj/project.pbxproj: Added.
        * WebKitLauncher/WebKitNightlyEnabler.m: Added.  This makes
          up the WebKitNightlyEnabler dylib which is loaded into Safari's address space
          to cause LaunchServices to treat Safari.app as WebKit.app when it is run from
          the nightly launcher.
        * WebKitLauncher/main.m: Added.  The WebKit.app launcher.
          It sets up the environment to have Safari use the bundled frameworks
          and load the WebKitNightlyEnabler dylib before exec'ing Safari
        * WebKitLauncher/start.html: Added.
        * WebKitLauncher/webkit.icns: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@13710 268f45cc-cd09-0410-ab3c-d52691b4dbfc