[unittest] Fix some unintentional behaviour in EditingTest

I haven't found any cases where this changes the visible behaviour of
the test, but having the file remain open across invocations was
certainly unexpected and affects how the first part of the test works at
runtime.

Author: benlangmuir

unittests/SourceKit/SwiftLang/EditingTest.cpp

@@ -253,7 +253,7 @@ void EditTest::doubleOpenWithDelay(useconds_t delay, bool closeDoc) {
   // be queried, since the semantic info from the first open is unreachable.
   for (int i = 0; i < 2; ++i) {
     bool expired = waitForDocUpdate(/*reset=*/true);
-    ASSERT_FALSE(expired) << "no second notification";
+    ASSERT_FALSE(expired) << "no " << (i ? "second " : "") << "notification";
     replaceText(DocName, 0, 0, StringRef(), Consumer);
     if (!Consumer.Diags.empty())
       break;
@@ -262,6 +262,8 @@ void EditTest::doubleOpenWithDelay(useconds_t delay, bool closeDoc) {
 
   ASSERT_EQ(1u, Consumer.Diags.size());
   EXPECT_STREQ("use of unresolved identifier 'unknown_name'", Consumer.Diags[0].Description.c_str());
+
+  close(DocName);
 }
 
 // This test is failing occassionally in CI: rdar://42483323