32 bpp floating point textures

This is VERY preliminary, but it was sufficient for me to get 32 bit floating point textures in a sample app

BUG=skia:
R=bsalomon@chromium.org, bsalomon@google.com

Author: joshualitt@chromium.org

Review URL: https://codereview.chromium.org/359803003
diff --git a/gyp/tests.gypi b/gyp/tests.gypi
index ec12461..99a52a4 100644
--- a/gyp/tests.gypi
+++ b/gyp/tests.gypi
@@ -75,6 +75,7 @@
     '../tests/FitsInTest.cpp',
     '../tests/FlatDataTest.cpp',
     '../tests/FlateTest.cpp',
+    '../tests/FloatingPointTextureTest.cpp',
     '../tests/FontHostStreamTest.cpp',
     '../tests/FontHostTest.cpp',
     '../tests/FontMgrTest.cpp',