Reland "VM: Simplify lowering of is-tests.""

runtime/vm/kernel_to_il.cc

Index: runtime/vm/kernel_to_il.cc
diff --git a/runtime/vm/kernel_to_il.cc b/runtime/vm/kernel_to_il.cc
index e817840567c9ea8c9600bd56c5488da07098fe54..969bccb21ef7120b2b829b83d4b87d807fb4619a 100644
--- a/runtime/vm/kernel_to_il.cc
+++ b/runtime/vm/kernel_to_il.cc
@@ -5027,13 +5027,10 @@ void FlowGraphBuilder::VisitIsExpression(IsExpression* node) {
     instructions += Constant(type);
     instructions += PushArgument();  // Type.
 
-    instructions += Constant(Bool::False());
-    instructions += PushArgument();  // Negate?.
-
     instructions +=
         InstanceCall(node->position(),
                      dart::Library::PrivateCoreLibName(Symbols::_instanceOf()),
-                     Token::kIS, 4);
+                     Token::kIS, 3);
   }
 
   fragment_ = instructions;
@@ -6123,12 +6120,10 @@ void FlowGraphBuilder::VisitTryCatch(class TryCatch* node) {
         catch_body += PushArgument();  // type arguments
         catch_body += Constant(*type_guard);
         catch_body += PushArgument();  // guard type
-        catch_body += Constant(Object::bool_false());
-        catch_body += PushArgument();  // negate
         catch_body += InstanceCall(
             TokenPosition::kNoSource,
             dart::Library::PrivateCoreLibName(Symbols::_instanceOf()),
-            Token::kIS, 4);
+            Token::kIS, 3);
 
         TargetEntryInstr* catch_entry;
         TargetEntryInstr* next_catch_entry;