Remove (untested) code for unsupported compilers.

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.
 
 # TODO(jochen): These will need to be user-settable to support standalone V8
 # builds.
 v8_compress_startup_data = "off"
 v8_deprecation_warnings = false
 v8_enable_disassembler = false
 v8_enable_gdbjit = false
@@ skipping 1300 matching lines @@
         defines += [ "V8_LIBRT_NOT_AVAILABLE" ]
       }
     }
   } else if (is_mac) {
     sources += [ "src/base/platform/platform-macos.cc" ]
   } else if (is_win) {
     # TODO(jochen): Add support for cygwin.
     sources += [
       "src/base/platform/platform-win32.cc",
       "src/base/win32-headers.h",
-      "src/base/win32-math.cc",
-      "src/base/win32-math.h",
     ]
 
     defines += [ "_CRT_RAND_S" ]  # for rand_s()
 
     libs = [ "winmm.lib", "ws2_32.lib" ]
   }
 
   # TODO(jochen): Add support for qnx, freebsd, openbsd, netbsd, and solaris.
 }
 
@@ skipping 107 matching lines @@
     deps = [
       ":v8_base",
       ":v8_nosnapshot",
     ]
   }
 
   direct_dependent_configs = [ ":external_config" ]
 }
 
 }