Revert 34983 - Split more targets from chrome.gyp to add support for building...

Revert 34983 - Split more targets from chrome.gyp to add support for building Native Client for 64bit Windows. 

This CL is required for supporting Native Client on 64bit Windows. On Win64 we will use a 64bit executable to load NaCl modules. Since we have only one version of Chrome on Windows, this executable has to be built together with 32bit Chrome binaries.
For the targets that are required for both 32bit and 64bit builds, this CL moves the shared parts of the target definitions into targetspecific gypi files (such as base.gypi). New 64bit only targets are added. Since we would like to port as few code as possible at this point, some 64bit targets include less source files or less dependencies than the original 32bit targets. These targets will have nacl_win64 in their name  to emphasize that they should be used for NaCl only. Some 64bit targets are identical to the 32bit targets in everything except for the target platform  these will have only win64 in their name. 

TEST=none
BUG=28176
Review URL: http://codereview.chromium.org/384068

TBR=gregoryd@google.com


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=34990