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..b1f1da582c8014fe3ad17fff18c77bd76e20d4cd 100644
--- a/frog/leg/ssa/codegen.dart
+++ b/frog/leg/ssa/codegen.dart
@@ -33,6 +33,7 @@ class SsaCodeGeneratorTask extends CompilerTask {
     // since we don't do code motion after this point.
     new SsaCheckInstructionUnuser().visitGraph(graph);
     new SsaConditionMerger().visitGraph(graph);
+      // JavaScript only supports characters in the BMP.
     new SsaPhiEliminator().visitGraph(graph);
     if (GENERATE_SSA_TRACE) {
       new HTracer.singleton().traceGraph("no-phi", graph);
@@ -460,11 +461,6 @@ 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 +468,13 @@ 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,
+                          (String reason) {
+                               compiler.cancel(reason, instruction: node);
+                          });
+      buffer.add(quote);
     } else {
       buffer.add(node.value);
     }