VM: [Kernel] Implement CatchBlockEntryInstr::should_restore_closure_context on all platforms.

runtime/vm/flow_graph_compiler.h

Index: runtime/vm/flow_graph_compiler.h
diff --git a/runtime/vm/flow_graph_compiler.h b/runtime/vm/flow_graph_compiler.h
index 313691504ff9eba4446bed12c7382c12f1ce7162..7262d0e9c03589ab3ea89fe9f7cd40f2a74a2dc7 100644
--- a/runtime/vm/flow_graph_compiler.h
+++ b/runtime/vm/flow_graph_compiler.h
@@ -540,6 +540,11 @@ class FlowGraphCompiler : public ValueObject {
 
   // If the cid does not fit in 16 bits, then this will cause a bailout.
   uint16_t ToEmbeddableCid(intptr_t cid, Instruction* instruction);
+
+  // In optimized code, variables at the catch block entry reside at the top
+  // of the allocatable register range.
+  // Must be in sync with FlowGraphAllocator::ProcessInitialDefinition.
+  intptr_t CatchEntryRegForVariable(const LocalVariable& var);
 #endif  // defined(TARGET_ARCH_DBC)
 
   CompilerDeoptInfo* AddDeoptIndexAtCall(intptr_t deopt_id);