[V8] Use previous token location as EOS token location

src/messages.js

Index: src/messages.js
diff --git a/src/messages.js b/src/messages.js
index e997061fc47416b04992090cef81a6fd8d7d7452..034237466ee3b05d6dd6351475488eb88235f6e5 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -401,10 +401,15 @@ function ScriptLineFromPosition(position) {
   var line_ends = this.line_ends;
 
   // We'll never find invalid positions so bail right away.
-  if (position > line_ends[upper]) {
+  if (position - 1 > line_ends[upper]) {

[yurys, 2015/04/27 09:23:15]

I'd rather v8 highlighted position of the last token before EOS one. EOS is
oftentimes very confusing for the user as it gives little information about what
construction of the language is incomplete. Is there a way to provide position
of the token that goes before eos as the error position?

     return -1;
   }
 
+  // Process EOS token
+  if (position > line_ends[upper]) {
+    return upper;
+  }
+
   // This means we don't have to safe-guard indexing line_ends[i - 1].
   if (position <= line_ends[0]) {
     return 0;