Drop icudata from the dependency list from web.gyp

Specifying icuuc is sufficient because icuuc depends on icudata.
Moreover, it causes ninja to complain about multiple rules specified for
icudata and a circular dependency when icu_use_data_file_flag is set to
1 on Linux.

See also https://codereview.chromium.org/89863002/

BUG=72633
TEST=All types of builds (static, shared, etc) go fine.

Review URL: https://codereview.chromium.org/93053003

git-svn-id: svn://svn.chromium.org/blink/trunk@163104 bbb929c8-8fbe-4397-9dbb-9b2b20218538