Merge all gl::Texture* classes.

The validation for sampler completeness had a lot of duplicated code.
The special cases have been merged into the base class by checking mTarget.

BUG=angle:681

Change-Id: I11d94c1432f8fc70a1edaaf8228bbc43c3c8fff3
Reviewed-on: https://chromium-review.googlesource.com/236932
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/validationES.cpp b/src/libANGLE/validationES.cpp
index 51b8d9a..9e3224c 100644
--- a/src/libANGLE/validationES.cpp
+++ b/src/libANGLE/validationES.cpp
@@ -1259,7 +1259,7 @@
         return false;
     }
 
-    gl::Texture *texture = context->getTargetTexture(IsCubemapTextureTarget(target) ? GL_TEXTURE_CUBE_MAP : target);
+    gl::Texture *texture = context->getTargetTexture(IsCubeMapTextureTarget(target) ? GL_TEXTURE_CUBE_MAP : target);
     if (!texture)
     {
         context->recordError(Error(GL_INVALID_OPERATION));
@@ -1298,7 +1298,7 @@
     }
     else
     {
-        if (IsCubemapTextureTarget(target) && width != height)
+        if (IsCubeMapTextureTarget(target) && width != height)
         {
             context->recordError(Error(GL_INVALID_VALUE));
             return false;