Implement string interpolation up to SSA.

dart/frog/leg/ssa/builder.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class SsaBuilderTask extends CompilerTask {
   SsaBuilderTask(Compiler compiler) : super(compiler);
   String get name() => 'SSA builder';
 
   HGraph build(FunctionElement element, TreeElements elements) {
     return measure(() {
@@ skipping 936 matching lines @@
     HBasicBlock joinBlock = addNewBlock();
     thenBlock.addSuccessor(joinBlock);
     elseBlock.addSuccessor(joinBlock);
     open(joinBlock);
 
     definitions = joinDefinitions(joinBlock, thenDefinitions, definitions);
     HPhi phi = new HPhi.manyInputs(null, [thenInstruction, elseInstruction]);
     joinBlock.addPhi(phi);
     stack.add(phi);
   }
+
+  visitStringInterpolation(StringInterpolation node) {
+    compiler.unimplemented('SsaBuilder.visitStringInterpolation', node: node);
+  }
+
+  visitStringInterpolationPart(StringInterpolationPart node) {
+    compiler.unimplemented('SsaBuilder.visitStringInterpolationPart',
+                           node: node);
+  }
 }