Update libchromiumcontent for Windows support

* vendor/libchromiumcontent e70a88f...e94c8fb (59):
  > Merge branch 'master' of https://github.com/aroben/libchromiumcontent into windows
  > Copy s3put to a .py file on Windows
  > Invoke s3put correctly on Windows
  > Really get rid of ICU's global new/delete
  > Try a different way of removing ICU's operator new/delete
  > Revert "Try to remove ICU's internal operator new and delete"
  > Try to remove ICU's internal operator new and delete
  > Fix target name
  > Fix typo
  > Try to handle utf8_countTrailBytes differently for sqlite3
  > Export utf8_countTrailBytes for sqlite's benefit
  > Let the shell find dumpbin.exe
  > Make sure dumpbin.exe is on PATH
  > PEP8-ify gyp-win-tool-wrapper
  > Fix build error in dom_storage_message_filter.cc
  > Fix build error in ppapi_decryptor.cc
  > Revert "Do a standard, non-component build on Windows"
  > Only copy files into src/chromiumcontent if they've changed
  > Merge branch 'master' of https://github.com/aroben/libchromiumcontent into windows
  > Skip uploading symbols for now
  > Fix typo
  > Copy the right binaries on Windows
  > Revert "Make sure we always run gclient hooks"
  > Do a standard, non-component build on Windows
  > More sys.executable usage
  > Revert "Make ninja verbose for debugging"
  > Make sure we always run gclient hooks
  > Disable NaCl before calling `gclient sync`
  > Fix setting of GYP_DEFINES
  > Disable NaCl to try to fix the Windows build
  > Revert "Try putting depot_tools in PATH before building"
  > Try putting depot_tools in PATH before building
  > Use sys.executable instead of relying on Python being in PATH
  > Make ninja verbose for debugging
  > Pull in environment variables from env.bat
  > Use the right option flag
  > Uh, use the right platform name
  > Make sure to install win_toolchain in the right place
  > Set up the win_toolchain directory when updating, if needed
  > Invoke Python explicitly when running scripts
  > Find the s3credentials file on Windows
  > Upload zip files to a platform-specific location
  > A few more defines
  > Another define for Windows
  > More defines for Windows
  > Turn off the custom allocator
  > Turn off incremental linking
  > Don't export base's kEventLogId
  > Don't export symbols from ICU
  > Sort exports in the .def file
  > More defines needed to build on Windows
  > Get things closer to building on Windows
  > Give chromiumcontent.dll a .def file
  > Don't build test_support_chromiumcontent on Windows (yet)
  > Use ninja.exe on Windows
  > Add a do-nothing DllMain function for Windows
  > Silence warnings about needing to export scoped_ptr
  > Don't build base/debug/debug_on_start_win.cc
  > Add preprocessor defines for building on Windows
Make script/build actually run gyp on Windows

We don't yet build, but we're getting closer.
Ignore .sln/.vcproj files created by gyp
Use MSBuild to build on Windows