Inserted string validation as separate task in compiler.

frog/leg/compiler.dart

Index: frog/leg/compiler.dart
diff --git a/frog/leg/compiler.dart b/frog/leg/compiler.dart
index 85888c1a0e9ced5fc5ad1c92270778ddd175a2eb..89916a69d2fae8f3d78fec413f716663d54efd03 100644
--- a/frog/leg/compiler.dart
+++ b/frog/leg/compiler.dart
@@ -49,6 +49,7 @@ class Compiler implements Canceler, Logger {
   List<CompilerTask> tasks;
   ScannerTask scanner;
   ParserTask parser;
+  StringValidatorTask stringValidator;
   TreeValidatorTask validator;
   ResolverTask resolver;
   TypeCheckerTask checker;
@@ -69,6 +70,7 @@ class Compiler implements Canceler, Logger {
     compileTimeConstantHandler = new CompileTimeConstantHandler(this);
     scanner = new ScannerTask(this);
     parser = new ParserTask(this);
+    stringValidator = new StringValidatorTask(this);
     validator = new TreeValidatorTask(this);
     resolver = new ResolverTask(this);
     checker = new TypeCheckerTask(this);
@@ -76,8 +78,8 @@ class Compiler implements Canceler, Logger {
     optimizer = new SsaOptimizerTask(this);
     generator = new SsaCodeGeneratorTask(this);
     emitter = new CodeEmitterTask(this);
-    tasks = [scanner, parser, resolver, checker, builder, optimizer, generator,
-             emitter, compileTimeConstantHandler];
+    tasks = [scanner, parser, stringValidator, resolver, checker, builder,
+             optimizer, generator, emitter, compileTimeConstantHandler];
   }
 
   void ensure(bool condition) {
@@ -183,6 +185,7 @@ class Compiler implements Canceler, Logger {
 
   TreeElements analyzeElement(Element element) {
     Node tree = parser.parse(element);
+    stringValidator.validate(tree);
     validator.validate(tree);
     TreeElements elements = resolver.resolve(element);
     checker.check(tree, elements);
@@ -248,13 +251,15 @@ class Compiler implements Canceler, Logger {
   }
 
   Element resolveType(ClassElement element) {
-    parser.parse(element);
+    Node tree = parser.parse(element);
+    stringValidator.validate(tree);
     resolver.resolveType(element);
     return element;
   }
 
   Element resolveSignature(FunctionElement element) {
-    parser.parse(element);
+    Node tree = parser.parse(element);
+    stringValidator.validate(tree);
     resolver.resolveSignature(element);
     return element;
   }