WebKit build needs to be told where to look for ICU package.

Chromium already sets this variable in common.gypi which is force included to all gyp files in the build.

Review URL: http://codereview.chromium.org/6250025

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6433 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/extensions/experimental/experimental.gyp

@@ -27,7 +27,10 @@
 
 {
   'variables': {
-    'icu_src_dir%': '',
+    # TODO(cira): Find out how to pass this value for arbitrary embedder.
+    # Chromium sets it in common.gypi and does force include of that file for
+    # all sub projects.
+    'icu_src_dir%': '../../../../third_party/icu',
   },
   'targets': [
     {