Add 💥 (😢 → 54, 😀 → 5107) in swift::FunctionType::get(…)

Add test case for crash triggered in `swift::FunctionType::get(…)`.

<details>
<summary>Stack trace:</summary>
```
4  swift           0x000000000100595b swift::FunctionType::get(swift::Type, swift::Type, swift::AnyFunctionType::ExtInfo const&) + 27
5  swift           0x0000000000f3d4a5 swift::constraints::ConstraintSystem::getTypeOfMemberReference(swift::Type, swift::ValueDecl*, bool, bool, swift::constraints::ConstraintLocatorBuilder, swift::DeclRefExpr const*, llvm::DenseMap<swift::CanType, swift::TypeVariableType*, llvm::DenseMapInfo<swift::CanType>, llvm::detail::DenseMapPair<swift::CanType, swift::TypeVariableType*> >*) + 2309
10 swift           0x0000000000efb560 swift::TypeChecker::inferDefaultWitnesses(swift::ProtocolDecl*) + 288
11 swift           0x0000000000ed3ee8 swift::finishTypeChecking(swift::SourceFile&) + 536
12 swift           0x0000000000c60d3a swift::CompilerInstance::performSema() + 3722
14 swift           0x00000000007d8429 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 2857
15 swift           0x00000000007a4458 main + 2872
Stack dump:
0.	Program arguments: /path/to/swift/bin/swift -frontend -c -primary-file validation-test/compiler_crashers/28351-swift-functiontype-get.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -module-name main -o /tmp/28351-swift-functiontype-get-b083da.o
<unknown>:0: error: unable to execute command: Segmentation fault
<unknown>:0: error: compile command failed due to signal (use -v to see invocation)
```
</details>

Author: practicalswift

validation-test/compiler_crashers/28351-swift-functiontype-get.swift

@@ -0,0 +1,9 @@
+// This source file is part of the Swift.org open source project
+// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+
+// RUN: not --crash %target-swift-frontend %s -parse
+extension A{{}protocol A}protocol A:class{protocol A{}typealias e:A