Hide Math function implementations in a closure.

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.
 
 # Because standalone V8 builds are not supported, assume this is part of a
 # Chromium build.
 import("//build/module_args/v8.gni")
 
 # TODO(jochen): These will need to be user-settable to support standalone V8
 # builds.
@@ skipping 155 matching lines @@
   # changes.
   inputs = [ "tools/jsmin.py" ]
 
   sources = [
     "src/runtime.js",
     "src/v8natives.js",
     "src/symbol.js",
     "src/array.js",
     "src/string.js",
     "src/uri.js",
+    "src/math.js",
     "src/third_party/fdlibm/fdlibm.js",
-    "src/math.js",
     "src/date.js",
     "src/regexp.js",
     "src/arraybuffer.js",
     "src/typedarray.js",
     "src/generator.js",
     "src/object-observe.js",
     "src/collection.js",
     "src/weak-collection.js",
     "src/collection-iterator.js",
     "src/promise.js",
@@ skipping 1369 matching lines @@
       sources += [
         "src/d8-debug.cc",
         "$target_gen_dir/d8-js.cc",
       ]
     }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
   }
 }