Introduce newline tokens into the token stream.

runtime/vm/scanner.h

Index: runtime/vm/scanner.h
diff --git a/runtime/vm/scanner.h b/runtime/vm/scanner.h
index 316ac98339e475cbda70bc57a0f8960df29d3f81..5d59dee190cc7da32621cba5ecc1976f5fbed032 100644
--- a/runtime/vm/scanner.h
+++ b/runtime/vm/scanner.h
@@ -203,6 +203,7 @@ class Scanner : ValueObject {
   static void PrintTokens(const GrowableTokenStream& ts);
 
   TokenDescriptor current_token_;  // Current token.
+  TokenDescriptor newline_token_;  // Newline token.
   const String& source_;           // The source text being tokenized.
   intptr_t source_length_;     // The length of the source text.
   intptr_t lookahead_pos_;     // Position of lookahead character
@@ -210,6 +211,7 @@ class Scanner : ValueObject {
   intptr_t token_start_;       // Begin of current token in src_.
   int32_t c0_;                 // Lookahead character.
   bool newline_seen_;          // Newline before current token.
+  intptr_t prev_token_line_;   // Line number of the previous token.
 
   // The following fields keep track whether we are scanning a string literal
   // and its interpolated expressions.