Remove unused flag from canUseScalarCheckedCast

Author: atrick

lib/SIL/Verifier/SILVerifier.cpp

@@ -3994,17 +3994,16 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
     }
   }
 
-  void verifyCheckedCast(bool isExact, SILType fromTy, SILType toTy,
-                         bool isOpaque = false) {
+  void verifyCheckedCast(bool isExact, SILType fromTy, SILType toTy) {
     // Verify common invariants.
     require(fromTy.isObject() && toTy.isObject(),
             "value checked cast src and dest must be objects");
 
     auto fromCanTy = fromTy.getASTType();
     auto toCanTy = toTy.getASTType();
 
-    require(isOpaque || canUseScalarCheckedCastInstructions(F.getModule(),
-                                                            fromCanTy, toCanTy),
+    require(canUseScalarCheckedCastInstructions(F.getModule(),
+                                                fromCanTy, toCanTy),
             "invalid value checked cast src or dest types");
 
     // Peel off metatypes. If two types are checked-cast-able, so are their