[ResultBuilders] Fix a crash in PreCheckResultBuilderApplication

Cant assume that `shouldTypeCheckInEnclosingExpression` always
implies a single expression closure anymore.

Author: xedin

lib/Sema/BuilderTransform.cpp

@@ -1970,7 +1970,7 @@ class PreCheckResultBuilderApplication : public ASTWalker {
         return nullptr;
 
       if (auto *closure = dyn_cast<ClosureExpr>(expr)) {
-        if (shouldTypeCheckInEnclosingExpression(closure)) {
+        if (closure->hasSingleExpressionBody()) {
           hasError |= containsErrorExpr(closure->getSingleExpressionBody());
           return hasError ? nullptr : expr;
         }