Issue=124

Part 1 of 5: <http://webkit.org/b/56337> Enable -Werror on ANGLE

Signed-off-by: Nicolas Capens
Signed-off-by: Daniel Koch

Upstream bug: <http://code.google.com/p/angleproject/issues/detail?id=124>

Fixes the following static analyzer warning:

    In file included from src/compiler/debug.cpp:14:
    In file included from src/compiler/ParseHelper.h:10:
    In file included from src/compiler/localintermediate.h:11:
    In file included from src/compiler/intermediate.h:21:
    src/compiler/ConstantUnion.h:56:17: warning: 7 enumeration values not handled in switch: 'EbtVoid', 'EbtGuardSamplerBegin', 'EbtSampler2D'... [-Wswitch-enum,2]
             switch (type) {
                     ^

* src/compiler/ConstantUnion.h:
(ConstantUnion::operator==): Added a default case.

Author:    David Kilzer <ddkilzer@apple.com>

git-svn-id: https://angleproject.googlecode.com/svn/trunk@572 736b8ea6-26fd-11df-bfd4-992fa37f6226