[swiftc (117 vs. 5256)] Add crasher in swift::TypeBase::getCanonicalType(...)

Add test case for crash triggered in `swift::TypeBase::getCanonicalType(...)`.

Current number of unresolved compiler crashers: 117 (5256 resolved)

Stack trace:

```
0 0x00000000034ba3f8 llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/path/to/swift/bin/swift+0x34ba3f8)
1 0x00000000034bab36 SignalHandler(int) (/path/to/swift/bin/swift+0x34bab36)
2 0x00007fd5d84a93e0 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x113e0)
3 0x0000000000e422d1 swift::TypeBase::getCanonicalType() (/path/to/swift/bin/swift+0xe422d1)
4 0x0000000000d3a9b0 (anonymous namespace)::FindCapturedVars::checkType(swift::Type, swift::SourceLoc) (/path/to/swift/bin/swift+0xd3a9b0)
5 0x0000000000d3ae1a (anonymous namespace)::FindCapturedVars::walkToExprPre(swift::Expr*) (/path/to/swift/bin/swift+0xd3ae1a)
6 0x0000000000dcd0b5 swift::ASTVisitor<(anonymous namespace)::Traversal, swift::Expr*, swift::Stmt*, bool, swift::Pattern*, bool, void>::visit(swift::Expr*) (/path/to/swift/bin/swift+0xdcd0b5)
7 0x0000000000dcf0f5 swift::ASTVisitor<(anonymous namespace)::Traversal, swift::Expr*, swift::Stmt*, bool, swift::Pattern*, bool, void>::visit(swift::Stmt*) (/path/to/swift/bin/swift+0xdcf0f5)
8 0x0000000000dcecd0 swift::ASTVisitor<(anonymous namespace)::Traversal, swift::Expr*, swift::Stmt*, bool, swift::Pattern*, bool, void>::visit(swift::Stmt*) (/path/to/swift/bin/swift+0xdcecd0)
9 0x0000000000dcb74e swift::Stmt::walk(swift::ASTWalker&) (/path/to/swift/bin/swift+0xdcb74e)
10 0x0000000000d39b54 swift::TypeChecker::computeCaptures(swift::AnyFunctionRef) (/path/to/swift/bin/swift+0xd39b54)
11 0x0000000000d3c487 (anonymous namespace)::FindCapturedVars::propagateCaptures(swift::AnyFunctionRef, swift::SourceLoc) (/path/to/swift/bin/swift+0xd3c487)
12 0x0000000000d3b20a (anonymous namespace)::FindCapturedVars::walkToExprPre(swift::Expr*) (/path/to/swift/bin/swift+0xd3b20a)
13 0x0000000000dcbf3b (anonymous namespace)::Traversal::doIt(swift::Decl*) (/path/to/swift/bin/swift+0xdcbf3b)
14 0x0000000000dd0cd4 (anonymous namespace)::Traversal::visitNominalTypeDecl(swift::NominalTypeDecl*) (/path/to/swift/bin/swift+0xdd0cd4)
15 0x0000000000dcbbc2 (anonymous namespace)::Traversal::doIt(swift::Decl*) (/path/to/swift/bin/swift+0xdcbbc2)
16 0x0000000000dcec68 swift::ASTVisitor<(anonymous namespace)::Traversal, swift::Expr*, swift::Stmt*, bool, swift::Pattern*, bool, void>::visit(swift::Stmt*) (/path/to/swift/bin/swift+0xdcec68)
17 0x0000000000dcb74e swift::Stmt::walk(swift::ASTWalker&) (/path/to/swift/bin/swift+0xdcb74e)
18 0x0000000000d39b54 swift::TypeChecker::computeCaptures(swift::AnyFunctionRef) (/path/to/swift/bin/swift+0xd39b54)
19 0x0000000000c66d9b typeCheckFunctionsAndExternalDecls(swift::TypeChecker&) (/path/to/swift/bin/swift+0xc66d9b)
20 0x0000000000c674a9 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int) (/path/to/swift/bin/swift+0xc674a9)
21 0x00000000009873d6 swift::CompilerInstance::performSema() (/path/to/swift/bin/swift+0x9873d6)
22 0x000000000047d3e9 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*) (/path/to/swift/bin/swift+0x47d3e9)
23 0x000000000047c2ec swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) (/path/to/swift/bin/swift+0x47c2ec)
24 0x000000000043ac17 main (/path/to/swift/bin/swift+0x43ac17)
25 0x00007fd5d6bc2830 __libc_start_main /build/glibc-Qz8a69/glibc-2.23/csu/../csu/libc-start.c:325:0
26 0x0000000000438059 _start (/path/to/swift/bin/swift+0x438059)
```

Author: practicalswift

validation-test/compiler_crashers/28562-swift-typebase-getcanonicaltype.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 https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+
+// RUN: not --crash %target-swift-frontend %s -emit-ir
+{class A{let f={return 0 &+ 1 a}}s