Inserted string validation as separate task in compiler.

frog/leg/scanner/parser.dart

Index: frog/leg/scanner/parser.dart
diff --git a/frog/leg/scanner/parser.dart b/frog/leg/scanner/parser.dart
index e1e581483d512245b0a9c4ec5f970ff0d311c1bf..7e8a54fa6d9451227ae984ddf60366549616ecb1 100644
--- a/frog/leg/scanner/parser.dart
+++ b/frog/leg/scanner/parser.dart
@@ -233,9 +233,9 @@ class Parser {
   }
 
 
-  Token parseString(Token token) {
+  Token parseStringPart(Token token) {
     if (token.kind === STRING_TOKEN) {
-      listener.handleLiteralString(token);
+      listener.handleStringPart(token);
       return token.next;
     } else {
       return listener.expected('string', token);
@@ -438,13 +438,13 @@ class Parser {
     listener.beginLibraryTag(token);
     token = parseIdentifier(token.next);
     token = expect('(', token);
-    token = parseString(token);
+    token = parseLiteralString(token);
     bool hasPrefix = false;
     if (optional(',', token)) {
       hasPrefix = true;
       token = parseIdentifier(token.next);
       token = expect(':', token);
-      token = parseString(token);
+      token = parseLiteralString(token);
     }
     token = expect(')', token);
     listener.endLibraryTag(hasPrefix, begin, token);
@@ -1195,16 +1195,17 @@ class Parser {
   }
 
   Token parseLiteralString(Token token) {
-    listener.handleLiteralString(token);
+    listener.beginLiteralString(token);
     token = token.next;
     int interpolationCount = 0;
     while (optional('\${', token)) {
-      token = parseExpression(token.next);
+      token = token.next;
+      token = parseExpression(token);
       token = expect('}', token);
-      token = parseString(token);
+      token = parseStringPart(token);
       ++interpolationCount;
     }
-    listener.handleStringInterpolationParts(interpolationCount);
+    listener.endLiteralString(interpolationCount);
     return token;
   }