Replace the GLVersion class with gl::Version.

Update code to use gl::Version in as many places as possible to ease ES 3.1
support.

BUG=angleproject:1588

Change-Id: I3490b53a81027cf849dac551a9cc66ce04506144
Reviewed-on: https://chromium-review.googlesource.com/404946
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/validationES31.cpp b/src/libANGLE/validationES31.cpp
index 7d5bb4f..4cea05e 100644
--- a/src/libANGLE/validationES31.cpp
+++ b/src/libANGLE/validationES31.cpp
@@ -19,7 +19,7 @@
 
 bool ValidateGetBooleani_v(Context *context, GLenum target, GLuint index, GLboolean *data)
 {
-    if (!context->getGLVersion().isES31())
+    if (context->getClientVersion() < ES_3_1)
     {
         context->handleError(Error(GL_INVALID_OPERATION, "Context does not support GLES3.1"));
         return false;
@@ -40,7 +40,7 @@
                                       GLsizei *length,
                                       GLboolean *data)
 {
-    if (!context->getGLVersion().isES31())
+    if (context->getClientVersion() < ES_3_1)
     {
         context->handleError(Error(GL_INVALID_OPERATION, "Context does not support GLES3.1"));
         return false;