Merge pull request #687 from practicalswift/re-add-sourcekit-bug-024-as-crash

Re-add SourceKit crash previously marked as fixed

Author: gribozavr

validation-test/IDE/crashers/024-swift-archetypebuilder-potentialarchetype-getrepresentative.swift

@@ -0,0 +1,4 @@
+// RUN: not --crash %target-swift-ide-test -code-completion -code-completion-token=A -source-filename=%s
+protocol c{func a:P
+protocol P{#^A^#func a:b
+typealias b:a