When a catch is unreachable, use the canonical empty array instead of null as its type array.

runtime/vm/precompiler.cc

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/precompiler.h"
 
 #include "vm/aot_optimizer.h"
 #include "vm/assembler.h"
 #include "vm/ast_printer.h"
 #include "vm/branch_optimizer.h"
@@ skipping 563 matching lines @@
   Code& code = Code::Handle(Z, function.CurrentCode());
   if (code.IsNull()) {
     ASSERT(function.kind() == RawFunction::kSignatureFunction);
   } else {
     const ExceptionHandlers& handlers =
         ExceptionHandlers::Handle(Z, code.exception_handlers());
     if (!handlers.IsNull()) {
       Array& types = Array::Handle(Z);
       for (intptr_t i = 0; i < handlers.num_entries(); i++) {
         types = handlers.GetHandledTypes(i);
-        if (!types.IsNull()) {
-          for (intptr_t j = 0; j < types.Length(); j++) {
-            type ^= types.At(j);
-            AddType(type);
-          }
+        for (intptr_t j = 0; j < types.Length(); j++) {
+          type ^= types.At(j);
+          AddType(type);
         }
       }
     }
   }
   // A function can always be inlined and have only a nested local function
   // remain.
   const Function& parent = Function::Handle(Z, function.parent_function());
   if (!parent.IsNull()) {
     AddTypesOf(parent);
   }
@@ skipping 1938 matching lines @@
       CompilationPipeline::New(thread->zone(), function);
 
   ASSERT(FLAG_precompiled_mode);
   const bool optimized = function.IsOptimizable();  // False for natives.
   return PrecompileFunctionHelper(pipeline, function, optimized);
 }
 
 #endif  // DART_PRECOMPILER
 
 }  // namespace dart