Update angle to a1851e8.

This includes the following changes:
a1851e8  Fixes for re-enabling more MSVC level 4 warnings: angle/ edition
6518fe2  Moved TextureStorage and Image into d3d
d4cfa57  Move more draw call validation to the API.
f6d38b0  Fix CollectVariablesTest GCC/Clang compile errors.
4e1fd41  Store a map of interface block registers.
829e89e  Add a default constructor to sh::ShaderVariable.
d5512cd  Collect shader outputs and interface block information.
0b7e5d8  Fix 64-bit warnings.
c0b9ef4  Split Caps into Caps, Extensions and TextureFormatCaps.
57f9b6d  Clean up generatemip.h.
86846e2  Clean up the functions in loadimage.h/cpp.
2a6564e  Fix build errors in validationES.cpp.
e92a354  Remove redundant FBO query methods.
55ec3b1  Refactor common attachment validation to base method.
23a8a43b  Store compact and expanded shader variables.
aae65a4  Add caps for texture size limits and other caps in the 6.28 table.
77f7485  Add a GetVariableInfo helper method.
93455eb  Add missing limits include to angleutils.h
4667c45  Refactor style in VariableInfo.cpp.
53cb14d  Share ArrayString and Str helper methods.
b23375f  Fixed an issue with Streaming Vertex data overflowing it's buffer.
aa7e166  Improve the const correctness.
b447227  Add a ValidateAttachmentTarget helper method.
570f7c8  Add helper methods for FBO attachment validation.
a328d56  Removed sampler state getters and setters from gl::Texture

BUG=none
TEST=none

Review URL: https://codereview.chromium.org/399733006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283877 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -69,7 +69,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
-  "angle_revision": "787fc03f15a0c4440d023659f267175fa3979808",
+  "angle_revision": "a1851e8fbb596b5cd8da1ba585ce69641f7f3337",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
   # and whatever else without interference from each other.