Add es3.1 shader constants

The patch adds all shader built-in constants.

BUG=angleproject:1442

TEST=angle_unittests
TEST=angle_end2end_tests

Change-Id: I81cae479d6506a8faa2dce023d5fcc2c1291d521
Reviewed-on: https://chromium-review.googlesource.com/364460
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/SymbolTable.cpp b/src/compiler/translator/SymbolTable.cpp
index f578909..059c5c7 100644
--- a/src/compiler/translator/SymbolTable.cpp
+++ b/src/compiler/translator/SymbolTable.cpp
@@ -88,7 +88,9 @@
 
     do
     {
-        if (level == ESSL3_BUILTINS && shaderVersion != 300)
+        if (level == ESSL3_1_BUILTINS && shaderVersion != 310)
+            level--;
+        if (level == ESSL3_BUILTINS && shaderVersion < 300)
             level--;
         if (level == ESSL1_BUILTINS && shaderVersion != 100)
             level--;
@@ -110,7 +112,9 @@
 {
     for (int level = LAST_BUILTIN_LEVEL; level >= 0; level--)
     {
-        if (level == ESSL3_BUILTINS && shaderVersion != 300)
+        if (level == ESSL3_1_BUILTINS && shaderVersion != 310)
+            level--;
+        if (level == ESSL3_BUILTINS && shaderVersion < 300)
             level--;
         if (level == ESSL1_BUILTINS && shaderVersion != 100)
             level--;