Fix 56 hints in pkg/compiler

pkg/compiler/lib/src/scanner/parser.dart

Index: pkg/compiler/lib/src/scanner/parser.dart
diff --git a/pkg/compiler/lib/src/scanner/parser.dart b/pkg/compiler/lib/src/scanner/parser.dart
index 7957b5e929335a86fe54b2ecd214e6636d08c885..9098587a45bef343bfbc5a39c7f27ebb076919a2 100644
--- a/pkg/compiler/lib/src/scanner/parser.dart
+++ b/pkg/compiler/lib/src/scanner/parser.dart
@@ -399,7 +399,6 @@ class Parser {
   }
 
   Token parseTypeOpt(Token token) {
-    String value = token.stringValue;
     Token peek = peekAfterIfType(token);
     if (peek != null && (peek.isIdentifier() || optional('this', peek))) {
       return parseType(token);
@@ -939,7 +938,6 @@ class Parser {
   ///     ['(', '*', 'operator']
   ///
   Link<Token> findMemberName(Token token) {
-    Token start = token;
     Link<Token> identifiers = const Link<Token>();
 
     // `true` if 'get' has been seen.
@@ -1162,7 +1160,6 @@ class Parser {
 
   Token parseMember(Token token) {
     token = parseMetadataStar(token);
-    String value = token.stringValue;
     if (isFactoryDeclaration(token)) {
       return parseFactoryMethod(token);
     }
@@ -1339,8 +1336,6 @@ class Parser {
     token = token.next; // Skip 'factory'.
     token = parseConstructorReference(token);
     token = parseFormalParameters(token);
-    bool previousYieldIsKeyword = yieldIsKeyword;
-    bool previousAwaitIsKeyword = awaitIsKeyword;
     token = parseAsyncModifier(token);
     if (optional('=', token)) {
       token = parseRedirectingFactoryBody(token);