Revert "[Type checker] Recurse into statements when cleaning type variables."

This reverts commit 45db3e3.

Author: DougGregor

lib/Sema/TypeCheckConstraints.cpp

@@ -1301,6 +1301,12 @@ void CleanupIllFormedExpressionRAII::doIt(Expr *expr, ASTContext &Context) {
       }
       return true;
     }
+
+    // Don't walk into statements.  This handles the BraceStmt in
+    // non-single-expr closures, so we don't walk into their body.
+    std::pair<bool, Stmt *> walkToStmtPre(Stmt *S) override {
+      return { false, S };
+    }
   };
 
   if (expr)

validation-test/compiler_crashers_fixed/28413-swift-typebase-getcanonicaltype.swift renamed to validation-test/compiler_crashers/28413-swift-typebase-getcanonicaltype.swift

@@ -5,7 +5,7 @@
 // See http://swift.org/LICENSE.txt for license information
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// RUN: not %target-swift-frontend %s -parse
+// RUN: not --crash %target-swift-frontend %s -parse
 t c
 let : {{
 return $0

validation-test/compiler_crashers_fixed/28470-anonymous-namespace-verifier-verifychecked-swift-type-llvm-smallptrset-swift-arc.swift renamed to validation-test/compiler_crashers/28470-anonymous-namespace-verifier-verifychecked-swift-type-llvm-smallptrset-swift-arc.swift

@@ -5,7 +5,7 @@
 // See http://swift.org/LICENSE.txt for license information
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// RUN: not %target-swift-frontend %s -emit-ir
+// RUN: not --crash %target-swift-frontend %s -emit-ir
 guard{{return $0
 == Int
 p