Make compile-time errors catchable

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 371 matching lines @@
 
       // Clear these before dropping classes as they may hold onto otherwise
       // dead instances of classes we will remove or otherwise unused symbols.
       DropScriptData();
       I->object_store()->set_unique_dynamic_targets(Array::null_array());
       Class& null_class = Class::Handle(Z);
       I->object_store()->set_future_class(null_class);
       I->object_store()->set_completer_class(null_class);
       I->object_store()->set_stream_iterator_class(null_class);
       I->object_store()->set_symbol_class(null_class);
+      I->object_store()->set_compiletime_error_class(null_class);
     }
     DropClasses();
     DropLibraries();
 
     BindStaticCalls();
     SwitchICCalls();
 
     ShareMegamorphicBuckets();
     DedupStackmaps();
     DedupLists();
@@ skipping 2911 matching lines @@
 
   ASSERT(FLAG_precompiled_mode);
   const bool optimized = function.IsOptimizable();  // False for natives.
   DartPrecompilationPipeline pipeline(zone, field_type_map);
   return PrecompileFunctionHelper(&pipeline, function, optimized);
 }
 
 #endif  // DART_PRECOMPILER
 
 }  // namespace dart