Handle variable set in inferrer

pkg/compiler/lib/src/inferrer/builder_kernel.dart

 // Copyright (c) 2017, 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 'package:kernel/ast.dart' as ir;
 
 import '../closure.dart';
 import '../common.dart';
 import '../constants/constant_system.dart';
 import '../elements/entities.dart';
@@ skipping 131 matching lines @@
         break;
       case ir.AsyncMarker.SyncYielding:
         failedAt(
             _analyzedMember, "Unexpected async marker: ${node.asyncMarker}");
         break;
     }
     return _returnType;
   }
 
   @override
-  TypeInformation defaultExpression(ir.Expression expression) {
-    // TODO(efortuna): Remove when more is implemented.
+  TypeInformation defaultExpression(ir.Expression node) {
+    // TODO(johnniwinther): Make this throw to assert that all expressions are
+    // handled.
     return _types.dynamicType;
   }
 
   @override
+  TypeInformation defaultStatement(ir.Statement node) {
+    // TODO(johnniwinther): Make this throw to assert that all statements are
+    // handled.
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
   TypeInformation visitNullLiteral(ir.NullLiteral literal) {
     return _types.nullType;
   }
 
   @override
   TypeInformation visitBlock(ir.Block block) {
     for (ir.Statement statement in block.statements) {
       statement.accept(this);
       if (_locals.aborts) break;
     }
@@ skipping 61 matching lines @@
     } else {
       _locals.update(local, visit(node.initializer), node, type);
     }
     return null;
   }
 
   @override
   TypeInformation visitVariableGet(ir.VariableGet node) {
     return _locals.use(_localsMap.getLocalVariable(node.variable));
   }
+
+  @override
+  TypeInformation visitVariableSet(ir.VariableSet node) {
+    Local local = _localsMap.getLocalVariable(node.variable);
+    DartType type = _localsMap.getLocalType(_elementMap, local);
+    TypeInformation rhsType = visit(node.value);
+    _locals.update(local, rhsType, node, type);
+    return rhsType;
+  }
 }