Merge gl::Context and gl::ContextState.

This reduces the number of indrections when accessing the Extensions
or Caps structures. It will provide a small speed-up to some methods.
It also cleans up the code.

Bug: angleproject:2966
Change-Id: Idddac70758c42c1c2b75c885d0cacc8a5c458685
Reviewed-on: https://chromium-review.googlesource.com/c/1392391
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Markus Tavenrath <matavenrath@nvidia.com>
diff --git a/src/libANGLE/validationES1.cpp b/src/libANGLE/validationES1.cpp
index 1bef889..1d59579 100644
--- a/src/libANGLE/validationES1.cpp
+++ b/src/libANGLE/validationES1.cpp
@@ -1172,7 +1172,7 @@
 bool ValidatePopMatrix(Context *context)
 {
     ANGLE_VALIDATE_IS_GLES1(context);
-    const auto &stack = context->getGLState().gles1().currentMatrixStack();
+    const auto &stack = context->getState().gles1().currentMatrixStack();
     if (stack.size() == 1)
     {
         context->validationError(GL_STACK_UNDERFLOW, kMatrixStackUnderflow);
@@ -1184,7 +1184,7 @@
 bool ValidatePushMatrix(Context *context)
 {
     ANGLE_VALIDATE_IS_GLES1(context);
-    const auto &stack = context->getGLState().gles1().currentMatrixStack();
+    const auto &stack = context->getState().gles1().currentMatrixStack();
     if (stack.size() == stack.max_size())
     {
         context->validationError(GL_STACK_OVERFLOW, kMatrixStackOverflow);