embedded: Don't assume that when calling a function with witness-method convention an existential is involved

Fixes a wrong "cannot use a value of protocol type in embedded Swift" error.

Unfortunately I don't have a test file for this.

Author: eeckstein

lib/SIL/Utils/InstructionUtils.cpp

@@ -961,8 +961,6 @@ RuntimeEffect swift::getRuntimeEffect(SILInstruction *inst, SILType &impactType)
       rt |= RuntimeEffect::ObjectiveC | RuntimeEffect::MetaData;
       break;
     case SILFunctionTypeRepresentation::WitnessMethod:
-      rt |= RuntimeEffect::MetaData | RuntimeEffect::Existential;
-      break;
     case SILFunctionTypeRepresentation::CFunctionPointer:
     case SILFunctionTypeRepresentation::CXXMethod:
     case SILFunctionTypeRepresentation::Thin: