Add support for 2x2 matrices

src/gpu/glsl/GrGLSL.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLSL_DEFINED
 #define GrGLSL_DEFINED
 
@@ skipping 80 matching lines @@
         case kVoid_GrSLType:
             return "void";
         case kFloat_GrSLType:
             return "float";
         case kVec2f_GrSLType:
             return "vec2";
         case kVec3f_GrSLType:
             return "vec3";
         case kVec4f_GrSLType:
             return "vec4";
+        case kMat22f_GrSLType:
+            return "mat2";
         case kMat33f_GrSLType:
             return "mat3";
         case kMat44f_GrSLType:
             return "mat4";
         case kSampler2D_GrSLType:
             return "sampler2D";
         case kSamplerExternal_GrSLType:
             return "samplerExternalOES";
         case kSampler2DRect_GrSLType:
             return "sampler2DRect";
@@ skipping 244 matching lines @@
 
 /**
  * Does an inplace mul, *=, of vec4VarName by mulFactor.
  * A semicolon is added after the assignment.
  */
 void GrGLSLMulVarBy4f(SkString* outAppend, const char* vec4VarName, const GrGLSLExpr4& mulFactor);
 
 #include "GrGLSL_impl.h"
 
 #endif