Remove support for Object.observe

BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 if (is_android) {
@@ skipping 268 matching lines @@
     "src/js/symbol.js",
     "src/js/array.js",
     "src/js/string.js",
     "src/js/uri.js",
     "src/js/math.js",
     "src/third_party/fdlibm/fdlibm.js",
     "src/js/regexp.js",
     "src/js/arraybuffer.js",
     "src/js/typedarray.js",
     "src/js/iterator-prototype.js",
-    "src/js/object-observe.js",
     "src/js/collection.js",
     "src/js/weak-collection.js",
     "src/js/collection-iterator.js",
     "src/js/promise.js",
     "src/js/messages.js",
     "src/js/json.js",
     "src/js/array-iterator.js",
     "src/js/string-iterator.js",
     "src/js/templates.js",
     "src/js/spread.js",
@@ skipping 35 matching lines @@
   inputs = [
     "tools/jsmin.py",
   ]
 
   # NOSORT
   sources = [
     "src/js/macros.py",
     "src/messages.h",
     "src/js/harmony-atomics.js",
     "src/js/harmony-regexp-exec.js",
-    "src/js/harmony-object-observe.js",
     "src/js/harmony-sharedarraybuffer.js",
     "src/js/harmony-simd.js",
     "src/js/harmony-species.js",
     "src/js/harmony-unicode-regexps.js",
     "src/js/harmony-string-padding.js",
     "src/js/promise-extra.js",
   ]
 
   outputs = [
     "$target_gen_dir/experimental-libraries.cc",
@@ skipping 965 matching lines @@
     "src/runtime/runtime-generator.cc",
     "src/runtime/runtime-i18n.cc",
     "src/runtime/runtime-internal.cc",
     "src/runtime/runtime-interpreter.cc",
     "src/runtime/runtime-json.cc",
     "src/runtime/runtime-literals.cc",
     "src/runtime/runtime-liveedit.cc",
     "src/runtime/runtime-maths.cc",
     "src/runtime/runtime-numbers.cc",
     "src/runtime/runtime-object.cc",
-    "src/runtime/runtime-observe.cc",
     "src/runtime/runtime-operators.cc",
     "src/runtime/runtime-proxy.cc",
     "src/runtime/runtime-regexp.cc",
     "src/runtime/runtime-scopes.cc",
     "src/runtime/runtime-simd.cc",
     "src/runtime/runtime-strings.cc",
     "src/runtime/runtime-symbol.cc",
     "src/runtime/runtime-test.cc",
     "src/runtime/runtime-typedarray.cc",
     "src/runtime/runtime-uri.cc",
@@ skipping 822 matching lines @@
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [
     ":internal_config",
     ":libplatform_config",
     ":features",
     ":toolchain",
   ]
 }