Bring back SourceManager::rangeContainsCodeCompletionLoc()

Author: DougGregor

include/swift/Basic/SourceManager.h

@@ -103,6 +103,13 @@ class SourceManager {
            rangeContainsTokenLoc(Enclosing, Inner.End);
   }
 
+  /// Returns true if range \p R contains the code-completion location, if any.
+  bool rangeContainsCodeCompletionLoc(SourceRange R) const {
+    return CodeCompletionBufferID
+               ? rangeContainsTokenLoc(R, getCodeCompletionLoc())
+               : false;
+  }
+
   /// Returns the buffer ID for the specified *valid* location.
   ///
   /// Because a valid source location always corresponds to a source buffer,