Make multi-line comments not count when checking whether --> is first on a line.

src/scanner-base.h

Index: src/scanner-base.h
diff --git a/src/scanner-base.h b/src/scanner-base.h
index 02566ddebb6014a629c10b0095b8aa5984a82273..1368cb6a66610a040bffa480f6696a72cc1ec7e5 100644
--- a/src/scanner-base.h
+++ b/src/scanner-base.h
@@ -479,6 +479,12 @@ class JavaScriptScanner : public Scanner {
     return has_line_terminator_before_next_;
   }
 
+  // Returns true if there was no non-whitespace on the line before the
+  // peek'ed token.
+  bool next_is_first_on_line() const {
+    return next_is_first_on_line_;
+  }
+
   // Scans the input as a regular expression pattern, previous
   // character(s) must be /(=). Returns true if a pattern is scanned.
   bool ScanRegExpPattern(bool seen_equal);
@@ -529,7 +535,12 @@ class JavaScriptScanner : public Scanner {
   // Start position of the octal literal last scanned.
   Location octal_pos_;
 
+  // Whether there is a line terminator between the current proper
+  // token and the next one (ignoring whitespace tokens and comments).
   bool has_line_terminator_before_next_;
+  // Whether there is only whitespace (and not comments) on the current
+  // line until now.
+  bool next_is_first_on_line_;
 };