Add a type kind to TypedSelector. A typed selector can either be

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/builder.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/builder.dart	(revision 18249)
+++ sdk/lib/_internal/compiler/implementation/ssa/builder.dart	(working copy)
@@ -303,8 +303,10 @@
       // context.
       ClassElement cls = element.getEnclosingClass();
       DartType type = cls.computeType(builder.compiler);
-      HThis thisInstruction = new HThis(closureData.thisElement,
-                                        new HBoundedType.nonNull(type));
+      HThis thisInstruction = new HThis(
+          closureData.thisElement,
+          new HBoundedType(
+              type, isExact: false, canBeNull: false, isInterfaceType: false));
       builder.graph.thisInstruction = thisInstruction;
       builder.graph.entry.addAtEntry(thisInstruction);
       directLocals[closureData.thisElement] = thisInstruction;
@@ -426,7 +428,11 @@
         Element element = closureData.thisElement;
         ClassElement cls = element.enclosingElement.getEnclosingClass();
         DartType type = cls.computeType(builder.compiler);
-        cachedTypeOfThis = new HBoundedType.nonNull(type);
+        cachedTypeOfThis = new HBoundedType(
+            type,
+            canBeNull: false,
+            isExact: false,
+            isInterfaceType: false);
       }
       res.guaranteedType = cachedTypeOfThis;
     }
@@ -4023,7 +4029,9 @@
     pushInvokeHelper1(backend.getMapMaker(), keyValuePairs,
         new HType.fromBoundedType(compiler.mapClass.computeType(compiler),
                                   compiler,
-                                  false));
+                                  canBeNull: false,
+                                  isExact: false,
+                                  isInterfaceType: false));
   }
 
   visitLiteralMapEntry(LiteralMapEntry node) {
@@ -4612,7 +4620,11 @@
     if (!baseType.isClass()) return HType.UNKNOWN;
     ClassBaseType classBaseType = baseType;
     return new HType.fromBoundedType(
-        classBaseType.element.computeType(compiler), compiler, false);
+        classBaseType.element.computeType(compiler),
+        compiler,
+        canBeNull: false,
+        isExact: true,
+        isInterfaceType: false);
   }
 
   HType mapInferredType(ConcreteType concreteType) {
@@ -4632,7 +4644,12 @@
     } else if (type == native.SpecialType.JsArray) {
       return HType.READABLE_ARRAY;
     } else {
-      return new HType.fromBoundedType(type, compiler, false);
+      return new HType.fromBoundedType(
+          type,
+          compiler,
+          canBeNull: false,
+          isExact: false,
+          isInterfaceType: false);
     }
   }