kernel->ssa: implement assert statements

pkg/compiler/lib/src/ssa/graph_builder.dart

 // Copyright (c) 2016, 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.
 
 import '../compiler.dart';
 import '../elements/elements.dart';
+import '../io/source_information.dart';
 import '../js_backend/js_backend.dart';
 import '../resolution/tree_elements.dart';
+import '../tree/tree.dart' as ast;
 import '../types/types.dart';
 import 'jump_handler.dart';
 import 'locals_handler.dart';
 import 'nodes.dart';
+import 'ssa_branch_builder.dart';
 
 /// Base class for objects that build up an SSA graph.
 ///
 /// This contains helpers for building the graph and tracking information about
 /// the current state of the graph being built.
 abstract class GraphBuilder {
   /// Holds the resulting SSA graph.
   final HGraph graph = new HGraph();
 
   // TODO(het): remove this
@@ skipping 129 matching lines @@
     HParameterValue result = new HParameterValue(parameter, type);
     if (lastAddedParameter == null) {
       graph.entry.addBefore(graph.entry.first, result);
     } else {
       graph.entry.addAfter(lastAddedParameter, result);
     }
     lastAddedParameter = result;
     return result;
   }
 
+  void handleIf(
+      {ast.Node node,
+      void visitCondition(),
+      void visitThen(),
+      void visitElse(),
+      SourceInformation sourceInformation}) {
+    SsaBranchBuilder branchBuilder = new SsaBranchBuilder(this, compiler, node);
+    branchBuilder.handleIf(visitCondition, visitThen, visitElse,
+        sourceInformation: sourceInformation);
+  }
+
   HSubGraphBlockInformation wrapStatementGraph(SubGraph statements) {
     if (statements == null) return null;
     return new HSubGraphBlockInformation(statements);
   }
 
   HSubExpressionBlockInformation wrapExpressionGraph(SubExpression expression) {
     if (expression == null) return null;
     return new HSubExpressionBlockInformation(expression);
   }
 }