Handle escapes in string literals.

frog/leg/ssa/codegen.dart

Index: frog/leg/ssa/codegen.dart
diff --git a/frog/leg/ssa/codegen.dart b/frog/leg/ssa/codegen.dart
index fad8f53490ea5fd45fb44311d6566a5880cb33f8..55e60aa72e29b9b9516c787dcb4cd73b4c01b2a7 100644
--- a/frog/leg/ssa/codegen.dart
+++ b/frog/leg/ssa/codegen.dart
@@ -460,11 +460,6 @@ class SsaCodeGenerator implements HVisitor {
     buffer.add(')');
   }
 
-  static String makeStringLiteral(SourceString literal) {
-    // TODO(lrn): Escape string content.
-    return literal.toString();
-  }
-
   visitLiteral(HLiteral node) {
     if (node.isLiteralNull()) {
       buffer.add("(void 0)");
@@ -472,7 +467,10 @@ class SsaCodeGenerator implements HVisitor {
       buffer.add('(${node.value})');
     } else if (node.isLiteralString()) {
       QuotedString string = node.value;
-      string.printOn(buffer);
+      String quote = string.quoteChar;
+      buffer.add(quote);
+      string.writeEscaped(buffer, string.quoteCharCode);
+      buffer.add(quote);
     } else {
       buffer.add(node.value);
     }