Fix for NPE with StringLiteral in toString()

compiler/javatests/com/google/dart/compiler/parser/SyntaxTest.java

Index: compiler/javatests/com/google/dart/compiler/parser/SyntaxTest.java
diff --git a/compiler/javatests/com/google/dart/compiler/parser/SyntaxTest.java b/compiler/javatests/com/google/dart/compiler/parser/SyntaxTest.java
index 1478abaeaf37d08be71082fd2e01fc0d362e8374..2bc7035e715305843a0bd8caa7bb1758950185e3 100644
--- a/compiler/javatests/com/google/dart/compiler/parser/SyntaxTest.java
+++ b/compiler/javatests/com/google/dart/compiler/parser/SyntaxTest.java
@@ -20,6 +20,7 @@ import com.google.dart.compiler.ast.DartField;
 import com.google.dart.compiler.ast.DartFieldDefinition;
 import com.google.dart.compiler.ast.DartFunctionExpression;
 import com.google.dart.compiler.ast.DartIdentifier;
+import com.google.dart.compiler.ast.DartImportDirective;
 import com.google.dart.compiler.ast.DartIntegerLiteral;
 import com.google.dart.compiler.ast.DartMapLiteral;
 import com.google.dart.compiler.ast.DartMethodDefinition;
@@ -52,6 +53,15 @@ public class SyntaxTest extends AbstractParserTest {
         "export 'a.dart';"));
   }
 
+  public void test_importDirective_noUri() {
+    DartUnit unit = parseUnit("test.dart", Joiner.on("\n").join(
+        "library lib;",
+        "import;"),
+        ParserErrorCode.EXPECTED_TOKEN, 2, 7);
+    DartImportDirective dir = (DartImportDirective) unit.getDirectives().get(1);
+    System.out.println(dir.toSource());
+  }
+
   public void test_getter() {
     parseUnit("getter.dart", Joiner.on("\n").join(
         "class G {",