Fix restoring of contexts in inlined finally code

runtime/vm/flow_graph_builder.cc

 // Copyright (c) 2012, 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/flow_graph_builder.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/ast_printer.h"
 #include "vm/bit_vector.h"
 #include "vm/class_finalizer.h"
@@ skipping 4274 matching lines @@
 void EffectGraphVisitor::VisitInlinedFinallyNode(InlinedFinallyNode* node) {
   InlineBailout("EffectGraphVisitor::VisitInlinedFinallyNode (exception)");
   const intptr_t try_index = owner()->try_index();
   if (try_index >= 0) {
     // We are about to generate code for an inlined finally block. Exceptions
     // thrown in this block of code should be treated as though they are
     // thrown not from the current try block but the outer try block if any.
     intptr_t outer_try_index = node->try_index();
     owner()->set_try_index(outer_try_index);
   }
-  BuildRestoreContext(node->context_var());
+
+  // Note: do not restore the saved_try_context here since the inlined
+  // code is running at he context level of the return or jump instruction
+  // that follows the inlined code. See issue 22822.

[regis, 2015/03/16 22:26:14]

at he -> at the

I find the comment implying a context mismatch somewhat misleading. The reason
we do not need to restore the context is that an inlined finally is never used
as an exception handler, therefore the context is always already set on entry.
In other words, the inlined finally block is never the target of a long jump
that would find an uninitialized current context variable.  

 
   JoinEntryInstr* finally_entry =
       new(I) JoinEntryInstr(owner()->AllocateBlockId(), owner()->try_index());
   EffectGraphVisitor for_finally_block(owner());
   node->finally_block()->Visit(&for_finally_block);
 
   if (try_index >= 0) {
     owner()->set_try_index(try_index);
   }
 
@@ skipping 57 matching lines @@
   Report::MessageF(Report::kBailout,
                    Script::Handle(function.script()),
                    function.token_pos(),
                    "FlowGraphBuilder Bailout: %s %s",
                    String::Handle(function.name()).ToCString(),
                    reason);
   UNREACHABLE();
 }
 
 }  // namespace dart