Fix assert in IsKnownConstant importation

src/coreclr/jit/importercalls.cpp

@@ -3642,14 +3642,14 @@ GenTree* Compiler::impIntrinsic(CORINFO_CLASS_HANDLE    clsHnd,
                 if (op1->OperIsConst() || gtIsTypeof(op1))
                 {
                     // op1 is a known constant, replace with 'true'.
-                    retNode = gtNewIconNode(1);
+                    retNode = gtNewTrue();
                     JITDUMP("\nExpanding RuntimeHelpers.IsKnownConstant to true early\n");
                     // We can also consider FTN_ADDR here
                 }
                 else if (opts.OptimizationDisabled())
                 {
                     // It doesn't make sense to carry it as GT_INTRINSIC till Morph in Tier0
-                    retNode = gtNewIconNode(0);
+                    retNode = gtNewFalse();
                     JITDUMP("\nExpanding RuntimeHelpers.IsKnownConstant to false early\n");
                 }
                 else

src/coreclr/jit/morph.cpp

@@ -8419,12 +8419,14 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac, bool* optA
                     // We're lucky to catch a constant here while importer was not
                     JITDUMP("true\n");
                     DEBUG_DESTROY_NODE(tree, op1);
-                    tree = gtNewIconNode(1);
+                    tree = gtNewTrue();
                 }
                 else
                 {
                     JITDUMP("false\n");
-                    tree = gtWrapWithSideEffects(gtNewIconNode(0), op1, GTF_ALL_EFFECT);
+                    tree = gtNewFalse();
+                    tree->SetMorphed(this);
+                    tree = gtWrapWithSideEffects(tree, op1, GTF_ALL_EFFECT);
                 }
                 tree->SetMorphed(this);
                 return tree;