Implement EXT_shader_texture_lod

BUG=angle:551

Change-Id: I81d7574a15861f1b24ddf6147cf71adbf20e10f3
Reviewed-on: https://chromium-review.googlesource.com/194960
Tested-by: Nicolas Capens <nicolascapens@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
diff --git a/src/compiler/translator/ShaderLang.cpp b/src/compiler/translator/ShaderLang.cpp
index fe215b7..db37d21 100644
--- a/src/compiler/translator/ShaderLang.cpp
+++ b/src/compiler/translator/ShaderLang.cpp
@@ -89,6 +89,7 @@
     resources->ARB_texture_rectangle = 0;
     resources->EXT_draw_buffers = 0;
     resources->EXT_frag_depth = 0;
+    resources->EXT_shader_texture_lod = 0;
 
     // Disable highp precision in fragment shader by default.
     resources->FragmentPrecisionHigh = 0;