[swiftc (114 vs. 5184)] Add crasher in swift::Type::transform

Add test case for crash triggered in `swift::Type::transform`.

Current number of unresolved compiler crashers: 114 (5184 resolved)

Assertion failure in [`lib/AST/ASTContext.cpp (line 2619)`](https://github.com/apple/swift/blob/master/lib/AST/ASTContext.cpp#L2619):

```
Assertion `(!Parent || Parent->is<NominalType>() || Parent->is<BoundGenericType>() || Parent->is<UnboundGenericType>()) && "parent must be a nominal type"' failed.

When executing: static swift::NominalType *swift::NominalType::get(swift::NominalTypeDecl *, swift::Type, const swift::ASTContext &)
```

Assertion context:

```
  assert((isa<ProtocolDecl>(D) || !D->getGenericParams()) &&
         "must be a non-generic type decl");
  assert((!Parent || Parent->is<NominalType>() ||
          Parent->is<BoundGenericType>() ||
          Parent->is<UnboundGenericType>()) &&
         "parent must be a nominal type");

  switch (D->getKind()) {
  case DeclKind::Enum:
    return EnumType::get(cast<EnumDecl>(D), Parent, C);
  case DeclKind::Struct:
```
Stack trace:

```
#0 0x00000000031d10e8 llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/path/to/swift/bin/swift+0x31d10e8)
#1 0x00000000031d1936 SignalHandler(int) (/path/to/swift/bin/swift+0x31d1936)
#2 0x00007f1987b92330 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x10330)
#3 0x00007f1986350c37 gsignal /build/eglibc-oGUzwX/eglibc-2.19/signal/../nptl/sysdeps/unix/sysv/linux/raise.c:56:0
#4 0x00007f1986354028 abort /build/eglibc-oGUzwX/eglibc-2.19/stdlib/abort.c:91:0
#5 0x00007f1986349bf6 __assert_fail_base /build/eglibc-oGUzwX/eglibc-2.19/assert/assert.c:92:0
#6 0x00007f1986349ca2 (/lib/x86_64-linux-gnu/libc.so.6+0x2fca2)
#7 0x0000000000d012c8 (/path/to/swift/bin/swift+0xd012c8)
#8 0x0000000000de3cd1 swift::Type::transform(llvm::function_ref<swift::Type (swift::Type)>) const (/path/to/swift/bin/swift+0xde3cd1)
#9 0x0000000000cb24b0 swift::constraints::ConstraintSystem::getTypeOfReference(swift::ValueDecl*, bool, bool, swift::FunctionRefKind, swift::constraints::ConstraintLocatorBuilder, swift::DeclRefExpr const*) (/path/to/swift/bin/swift+0xcb24b0)
#10 0x0000000000cb4a30 swift::constraints::ConstraintSystem::resolveOverload(swift::constraints::ConstraintLocator*, swift::Type, swift::constraints::OverloadChoice) (/path/to/swift/bin/swift+0xcb4a30)
#11 0x0000000000c67cc9 swift::ASTVisitor<(anonymous namespace)::ConstraintGenerator, swift::Type, void, void, void, void, void>::visit(swift::Expr*) (/path/to/swift/bin/swift+0xc67cc9)
#12 0x0000000000c6e3c0 (anonymous namespace)::ConstraintWalker::walkToExprPost(swift::Expr*) (/path/to/swift/bin/swift+0xc6e3c0)
#13 0x0000000000d68941 (anonymous namespace)::Traversal::visit(swift::Expr*) (/path/to/swift/bin/swift+0xd68941)
#14 0x0000000000d6a312 (anonymous namespace)::Traversal::visit(swift::Expr*) (/path/to/swift/bin/swift+0xd6a312)
#15 0x0000000000d6a372 (anonymous namespace)::Traversal::visit(swift::Expr*) (/path/to/swift/bin/swift+0xd6a372)
#16 0x0000000000d659be swift::Expr::walk(swift::ASTWalker&) (/path/to/swift/bin/swift+0xd659be)
#17 0x0000000000c63ca8 swift::constraints::ConstraintSystem::generateConstraints(swift::Expr*) (/path/to/swift/bin/swift+0xc63ca8)
#18 0x0000000000c8d35d swift::constraints::ConstraintSystem::solve(swift::Expr*&, swift::Type, swift::ExprTypeCheckListener*, llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::FreeTypeVariableBinding) (/path/to/swift/bin/swift+0xc8d35d)
#19 0x0000000000b8ae7b swift::TypeChecker::solveForExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::FreeTypeVariableBinding, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem&, llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>) (/path/to/swift/bin/swift+0xb8ae7b)
#20 0x0000000000b8d96e swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem*) (/path/to/swift/bin/swift+0xb8d96e)
#21 0x0000000000c02594 swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) (/path/to/swift/bin/swift+0xc02594)
#22 0x0000000000c01665 (anonymous namespace)::StmtChecker::typeCheckBody(swift::BraceStmt*&) (/path/to/swift/bin/swift+0xc01665)
#23 0x0000000000c00993 swift::TypeChecker::typeCheckFunctionBodyUntil(swift::FuncDecl*, swift::SourceLoc) (/path/to/swift/bin/swift+0xc00993)
#24 0x0000000000c007e7 swift::TypeChecker::typeCheckAbstractFunctionBodyUntil(swift::AbstractFunctionDecl*, swift::SourceLoc) (/path/to/swift/bin/swift+0xc007e7)
#25 0x0000000000c01411 swift::TypeChecker::typeCheckAbstractFunctionBody(swift::AbstractFunctionDecl*) (/path/to/swift/bin/swift+0xc01411)
#26 0x0000000000c151f8 typeCheckFunctionsAndExternalDecls(swift::TypeChecker&) (/path/to/swift/bin/swift+0xc151f8)
#27 0x0000000000c15d8b swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int) (/path/to/swift/bin/swift+0xc15d8b)
#28 0x0000000000938c66 swift::CompilerInstance::performSema() (/path/to/swift/bin/swift+0x938c66)
#29 0x000000000047ece5 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*) (/path/to/swift/bin/swift+0x47ece5)
#30 0x000000000047db7f swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) (/path/to/swift/bin/swift+0x47db7f)
#31 0x000000000044509a main (/path/to/swift/bin/swift+0x44509a)
#32 0x00007f198633bf45 __libc_start_main /build/eglibc-oGUzwX/eglibc-2.19/csu/libc-start.c:321:0
#33 0x0000000000442816 _start (/path/to/swift/bin/swift+0x442816)
```

Author: practicalswift

validation-test/compiler_crashers/28487-parent-parent-is-nominaltype-parent-is-boundgenerictype-parent-is-unboundgeneric.swift

@@ -0,0 +1,10 @@
+// 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 -emit-ir
+// REQUIRES: asserts
+protocol w{struct b<T>{struct c{let f{_=f=e