Introduce a new gyp flag to warn about to be deprecated APIs

Makefile

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 131 matching lines @@
 endif
 # i18nsupport=off
 ifeq ($(i18nsupport), off)
   GYPFLAGS += -Dv8_enable_i18n_support=0
   TESTFLAGS += --noi18n
 endif
 # deprecation_warnings=on
 ifeq ($(deprecationwarnings), on)
   GYPFLAGS += -Dv8_deprecation_warnings=1
 endif
+# imminent_deprecation_warnings=on

[vogelheim, 2015/05/21 09:17:09]

spelling?

I take it the comment is meant to document the option, in which case it should
be spelled the same as the actual option. (That is, with the same number of
underscores.)

(Also, same issue above on deprecation_warnings, but not strictly relates to
your code.)

+ifeq ($(imminent_deprecationwarnings), on)
+  GYPFLAGS += -Dv8_imminent_deprecation_warnings=1
+endif
 # asan=on
 ifeq ($(asan), on)
   GYPFLAGS += -Dasan=1 -Dclang=1
   TESTFLAGS += --asan
   ifeq ($(lsan), on)
     GYPFLAGS += -Dlsan=1
   endif
 endif
 ifdef embedscript
   GYPFLAGS += -Dembed_script=$(embedscript)
@@ skipping 333 matching lines @@
 # We need to manually set the stack limit here, to work around bugs in
 # gmake-3.81 and global-5.7.1 on recent 64-bit Linux systems.
 GPATH GRTAGS GSYMS GTAGS: gtags.files $(shell cat gtags.files 2> /dev/null)
         @bash -c 'ulimit -s 10240 && GTAGSFORCECPP=yes gtags -i -q -f $<'
 
 gtags.clean:
         rm -f gtags.files GPATH GRTAGS GSYMS GTAGS
 
 dependencies builddeps:
         $(error Use 'gclient sync' instead)