Removing #ifdefs for WEB_AUDIO compile time flag.

Source/build/features.gypi

 #
 # Copyright (C) 2009 Google Inc. 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
@@ skipping 36 matching lines @@
       'blink_logging_always_on%': 0,
     },
     'conditions': [
       ['use_concatenated_impulse_responses==1', {
         # Use concatenated HRTF impulse responses
         'feature_defines': ['WTF_USE_CONCATENATED_IMPULSE_RESPONSES=1'],
       }],
       ['OS!="android"', {
         'feature_defines': [
           'ENABLE_INPUT_MULTIPLE_FIELDS_UI=1',
-          'ENABLE_WEB_AUDIO=1'
         ],
       }],
       # Mac OS X uses Accelerate.framework FFT by default instead of FFmpeg.
       ['OS!="mac" and OS!="android"', {
         'feature_defines': [
           'WTF_USE_WEBAUDIO_FFMPEG=1',
         ],
       }],
       ['OS=="android" and use_openmax_dl_fft!=0', {
         'feature_defines': [
           'WTF_USE_WEBAUDIO_OPENMAX_DL_FFT=1',
           # Enabling the FFT is enough to enable WebAudio support to
           # allow most WebAudio features to work on Android.
-          'ENABLE_WEB_AUDIO=1',

[Mike West, 2014/09/25 13:40:04]

Given the comments here, it's not at all clear that we can remove this
compile-time flag. kbr@, WDYT?

[Raymond Toy, 2014/09/25 17:43:18]

The comments should probably be updated.

I have personally tested webaudio on Android arm, arm64, x86, and mips. These
all build and run as expected. (I have not tested x86 or mips recently,
however.)

         ],
       }],
       # Mac OS X has not implemented support for ENABLE(OPENTYPE_VERTICAL) yet
       ['OS!="mac"', {
         'feature_defines': [
           'ENABLE_OPENTYPE_VERTICAL=1',
         ],
       }],
       ['use_default_render_theme==1', {
         'feature_defines': [
@@ skipping 18 matching lines @@
         ],
       }],
       ['blink_logging_always_on==1', {
         'feature_defines': [
           'LOG_DISABLED=0',
         ],
       }],
     ],
   },
 }