preprocessor: Check for line number overflow

Also remove dead code in Tokenizer.l

BUG=chromium:668842

Change-Id: Ice18313a64f0bb2242299993bfaa882a6578ad54
Reviewed-on: https://chromium-review.googlesource.com/435042
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/compiler/preprocessor/DiagnosticsBase.h b/src/compiler/preprocessor/DiagnosticsBase.h
index 0c2da1b..ea37614 100644
--- a/src/compiler/preprocessor/DiagnosticsBase.h
+++ b/src/compiler/preprocessor/DiagnosticsBase.h
@@ -63,6 +63,7 @@
         PP_INVALID_LINE_DIRECTIVE,
         PP_NON_PP_TOKEN_BEFORE_EXTENSION_ESSL3,
         PP_UNDEFINED_SHIFT,
+        PP_TOKENIZER_ERROR,
         PP_ERROR_END,
 
         PP_WARNING_BEGIN,