Fix --host-checked mode and add proper canBePrimitive method to HBoundedType.

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

Index: sdk/lib/_internal/compiler/implementation/ssa/types.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/types.dart b/sdk/lib/_internal/compiler/implementation/ssa/types.dart
index d4b2594859ec5dfcf9435c6e885e34f76b872de2..46e11eb8e6e3dce0d1252ede78e9b27fe153e12b 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/types.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/types.dart
@@ -914,6 +914,11 @@ class HBoundedType extends HType {
 
   bool canBeNull() => mask.isNullable;
 
+  bool canBePrimitive(Compiler compiler) {
+    // TODO(kasperl): Check for string, etc.
+    return canBePrimitiveArray(compiler);
+  }
+
   bool canBePrimitiveArray(Compiler compiler) {
     JavaScriptBackend backend = compiler.backend;
     DartType jsArrayType = backend.jsArrayClass.computeType(compiler);