Remove shouldWalkCaptureInitializerExpressions from PreCheckTarget

We walk into PatternBindingDecls, so I don't think
there should be any reason we can't walk captures
normally (i.e via their PBD).

Author: hamishknight

lib/Sema/PreCheckTarget.cpp

@@ -1107,8 +1107,6 @@ class PreCheckTarget final : public ASTWalker {
 
   bool walkToClosureExprPre(ClosureExpr *expr);
 
-  bool shouldWalkCaptureInitializerExpressions() override { return true; }
-
   MacroWalking getMacroWalkingBehavior() const override {
     return MacroWalking::Arguments;
   }