[wasm][asm.js] Adding custom asm.js lexer.

src/parsing/scanner.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Features shared by parsing and pre-parsing scanners.
 
 #ifndef V8_PARSING_SCANNER_H_
 #define V8_PARSING_SCANNER_H_
 
 #include "src/allocation.h"
@@ skipping 307 matching lines @@
   // Scans the input as a regular expression pattern, next token must be /(=).
   // Returns true if a pattern is scanned.
   bool ScanRegExpPattern();
   // Scans the input as regular expression flags. Returns the flags on success.
   Maybe<RegExp::Flags> ScanRegExpFlags();
 
   // Scans the input as a template literal
   Token::Value ScanTemplateStart();
   Token::Value ScanTemplateContinuation();
 
-  Handle<String> SourceUrl(Isolate* isolate) const {
-    Handle<String> tmp;
-    if (source_url_.length() > 0) tmp = source_url_.Internalize(isolate);
-    return tmp;
-  }
-
-  Handle<String> SourceMappingUrl(Isolate* isolate) const {
-    Handle<String> tmp;
-    if (source_mapping_url_.length() > 0)
-      tmp = source_mapping_url_.Internalize(isolate);
-    return tmp;
-  }
+  Handle<String> SourceUrl(Isolate* isolate) const;
+  Handle<String> SourceMappingUrl(Isolate* isolate) const;
 
   bool FoundHtmlComment() const { return found_html_comment_; }
 
  private:
   // Scoped helper for saving & restoring scanner error state.
   // This is used for tagged template literals, in which normally forbidden
   // escape sequences are allowed.
   class ErrorState;
 
   // Scoped helper for literal recording. Automatically drops the literal
@@ skipping 428 matching lines @@
   bool found_html_comment_;
 
   MessageTemplate::Template scanner_error_;
   Location scanner_error_location_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_SCANNER_H_