Do not hash mapping field names of a reserved struct.

With this fixed, Chrome behaves the same on WebGL conformance tests 1.0.2 with/without --enable-shader-name-hashing

BUG=
TEST=WebGL conformance tests
Review URL: https://codereview.appspot.com/7229043

git-svn-id: http://angleproject.googlecode.com/svn/trunk@1809 736b8ea6-26fd-11df-bfd4-992fa37f6226
Fix version.

TBR=alokp
Review URL: https://codereview.appspot.com/7228076

git-svn-id: http://angleproject.googlecode.com/svn/trunk@1810 736b8ea6-26fd-11df-bfd4-992fa37f6226