Fix the kasko gyp var declaration.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1125 matching lines @@
     'notifications%': '<(notifications)',
     'clang_use_chrome_plugins%': '<(clang_use_chrome_plugins)',
     'mac_want_real_dsym%': '<(mac_want_real_dsym)',
     'asan%': '<(asan)',
     'asan_blacklist%': '<(asan_blacklist)',
     'asan_coverage%': '<(asan_coverage)',
     'sanitizer_coverage%': '<(sanitizer_coverage)',
     'asan_field_padding%': '<(asan_field_padding)',
     'use_sanitizer_options%': '<(use_sanitizer_options)',
     'syzyasan%': '<(syzyasan)',
-    'kasko': '<(kasko)',
+    'kasko%': '<(kasko)',
     'syzygy_optimize%': '<(syzygy_optimize)',
     'lsan%': '<(lsan)',
     'msan%': '<(msan)',
     'msan_blacklist%': '<(msan_blacklist)',
     'msan_track_origins%': '<(msan_track_origins)',
     'tsan%': '<(tsan)',
     'tsan_blacklist%': '<(tsan_blacklist)',
     'ubsan%': '<(ubsan)',
     'ubsan_blacklist%': '<(ubsan_blacklist)',
     'ubsan_vptr%': '<(ubsan_vptr)',
@@ skipping 4842 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }