Sema: Fix malformed AST when both DynamicSelfType and opened existentials are involved

This worked for functions, but for properties, we did things in
the wrong order.

Fixes rdar://160816868.

Author: slavapestov

lib/Sema/CSApply.cpp

@@ -1809,7 +1809,6 @@ namespace {
       result = adjustTypeForDeclReference(result, resultTySelf,
                                           resultType(adjustedRefTySelf),
                                           locator);
-      closeExistentials(result, locator);
 
       // If the property is of dynamic 'Self' type, wrap an implicit
       // conversion around the resulting expression, with the destination
@@ -1821,6 +1820,8 @@ namespace {
             result, resultTy));
       }
 
+      closeExistentials(result, locator);
+
       // If we need to load, do so now.
       if (loadImmediately) {
         result = cs.addImplicitLoadExpr(result);

test/SILGen/dynamic_self_opened_existential.swift

@@ -0,0 +1,26 @@
+// RUN: %target-swift-emit-silgen %s
+
+public class C {
+  public func f() -> Self { return self }
+  public var v: Self { return self }
+  public subscript() -> Self { return self }
+
+  public func g1() {}
+}
+
+public protocol P {
+  func g2()
+}
+
+func f(_ p: any P & C) {
+  p.f().g1()
+  p.f().g2()
+
+  p.v.g1()
+  p.v.g2()
+
+  // FIXME
+  // p[].g1()
+  // p[].g2()
+}
+