[CS] Remove delaying logic for callAsFunction with trailing closure

It doesn't seem like this is necessary anymore.

Author: hamishknight

lib/Sema/CSSimplify.cpp

@@ -13940,26 +13940,6 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyApplicableFnConstraint(
     if (instance2->isTypeVariableOrMember())
       return formUnsolved();
 
-    auto *argumentsLoc = getConstraintLocator(
-        outerLocator.withPathElement(ConstraintLocator::ApplyArgument));
-
-    auto *argumentList = getArgumentList(argumentsLoc);
-    assert(argumentList);
-
-    // Cannot simplify construction of callable types during constraint
-    // generation when trailing closures are present because such calls
-    // have special trailing closure matching semantics. It's unclear
-    // whether trailing arguments belong to `.init` or implicit
-    // `.callAsFunction` in this case.
-    //
-    // Note that the constraint has to be activate so that solver attempts
-    // once constraint generation is done.
-    if (getPhase() == ConstraintSystemPhase::ConstraintGeneration &&
-        argumentList->hasAnyTrailingClosures() &&
-        instance2->isCallAsFunctionType(DC)) {
-      return formUnsolved(/*activate=*/true);
-    }
-
     // Construct the instance from the input arguments.
     auto simplified = simplifyConstructionConstraint(
         instance2, func1, subflags,