Add support for coverage=1 builds on iOS

Uses the same method as is used on Mac to enable coverage. Some sources
need to be removed in coverage mode due to a toolchain bug.

BUG=None


Review URL: https://chromiumcodereview.appspot.com/11111014

git-svn-id: http://src.chromium.org/svn/trunk/src/build@161633 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -1661,11 +1661,13 @@
       }],
       ['coverage!=0', {
         'conditions': [
-          ['OS=="mac"', {
+          ['OS=="mac" or OS=="ios"', {
             'xcode_settings': {
               'GCC_INSTRUMENT_PROGRAM_FLOW_ARCS': 'YES',  # -fprofile-arcs
               'GCC_GENERATE_TEST_COVERAGE_FILES': 'YES',  # -ftest-coverage
             },
+          }],
+          ['OS=="mac"', {
             # Add -lgcov for types executable, shared_library, and
             # loadable_module; not for static_library.
             # This is a delayed conditional.