[CS] Remove some uses of hasUnresolvedType in the solver

These should be unreachable now.

lib/Sema/CSBindings.cpp

@@ -115,7 +115,6 @@ static bool isGenericParameter(TypeVariableType *TypeVar) {
 bool PotentialBinding::isViableForJoin() const {
   return Kind == AllowedBindingKind::Supertypes &&
          !BindingType->hasLValueType() &&
-         !BindingType->hasUnresolvedType() &&
          !BindingType->hasTypeVariable() &&
          !BindingType->hasPlaceholder() &&
          !BindingType->hasUnboundGenericType() &&

lib/Sema/CSSimplify.cpp

@@ -300,7 +300,6 @@ static bool backwardScanAcceptsTrailingClosure(
       paramTy->is<ArchetypeType>() ||
       paramTy->is<AnyFunctionType>() ||
       paramTy->isTypeVariableOrMember() ||
-      paramTy->is<UnresolvedType>() ||
       paramTy->isAny();
 }
 
@@ -10109,8 +10108,7 @@ performMemberLookup(ConstraintKind constraintKind, DeclNameRef memberName,
 
   MemberLookupResult result;
 
-  if (instanceTy->isTypeVariableOrMember() ||
-      instanceTy->is<UnresolvedType>()) {
+  if (instanceTy->isTypeVariableOrMember()) {
     result.OverallResult = MemberLookupResult::Unsolved;
     return result;
   }

lib/Sema/CSSolver.cpp

@@ -1166,8 +1166,7 @@ void ConstraintSystem::shrink(Expr *expr) {
 
       auto base = collection.getPointer();
       auto isInvalidType = [](Type type) -> bool {
-        return type.isNull() || type->hasUnresolvedType() ||
-               type->hasError();
+        return type.isNull() || type->hasError();
       };
 
       // Array type.
@@ -1179,9 +1178,6 @@ void ConstraintSystem::shrink(Expr *expr) {
 
       // Map or Set or any other associated collection type.
       if (auto boundGeneric = dyn_cast<BoundGenericType>(base)) {
-        if (boundGeneric->hasUnresolvedType())
-          return boundGeneric;
-
         // Avoid handling InlineArray, building a tuple would be wrong, and
         // we want to eliminate shrink.
         if (boundGeneric->getDecl() == ctx.getInlineArrayDecl())
@@ -1290,9 +1286,7 @@ void ConstraintSystem::shrink(Expr *expr) {
         auto elementType = extractElementType(contextualType);
         // If we couldn't deduce element type for the collection, let's
         // not attempt to solve it.
-        if (!elementType ||
-            elementType->hasError() ||
-            elementType->hasUnresolvedType())
+        if (!elementType || elementType->hasError())
           return;
 
         contextualType = elementType;