Discard first line of multiline string if only whitespace

runtime/vm/scanner.h

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // Scanner class for the Dart language. The scanner reads source text
 // and produces a stream of tokens which is used by the parser.
 //
 
 #ifndef VM_SCANNER_H_
 #define VM_SCANNER_H_
@@ skipping 148 matching lines @@
 
   // Is this scanner currently scanning a string interpolation expression.
   bool IsNestedContext() const { return saved_context_ != NULL; }
   void PushContext();
   void PopContext();
 
   // Starts reading a string literal.
   void ScanLiteralString(bool is_raw);
 
   // Read the characters of a string literal.
-  void ScanLiteralStringChars(bool is_raw);
+  void ScanLiteralStringChars(bool is_raw, bool is_first_line);
 
   // Reads a fixed number of hexadecimal digits.
   bool ScanHexDigits(int digits, int32_t* value);
 
   // Reads a variable number of hexadecimal digits.
   bool ScanHexDigits(int min_digits, int max_digits, int32_t* value);
 
   // Reads an escaped code point from within a string literal.
   void ScanEscapedCodePoint(int32_t* escaped_char);
 
@@ skipping 35 matching lines @@
 
   SourcePosition c0_pos_;      // Source position of lookahead character c0_.
   KeywordTable keywords_[Token::numKeywords];
   Array& keyword_symbol_table_;  // Access to keyword symbols in object store.
 };
 
 
 }  // namespace dart
 
 #endif  // VM_SCANNER_H_