Fix try-finally for dead AST-branches in TurboFan.

src/compiler/control-builders.cc

Index: src/compiler/control-builders.cc
diff --git a/src/compiler/control-builders.cc b/src/compiler/control-builders.cc
index 6dba2d3ad6083756aef4fbc1e43d392b9e85465b..2ace441e61eac82a83439ed2155a599128a290fb 100644
--- a/src/compiler/control-builders.cc
+++ b/src/compiler/control-builders.cc
@@ -151,7 +151,7 @@ void BlockBuilder::EndBlock() {
 
 void TryCatchBuilder::BeginTry() {
   catch_environment_ = environment()->CopyAsUnreachable();
-  catch_environment_->Push(nullptr);
+  catch_environment_->Push(the_hole());
 }
 
 
@@ -178,7 +178,7 @@ void TryCatchBuilder::EndCatch() {
 
 void TryFinallyBuilder::BeginTry() {
   finally_environment_ = environment()->CopyAsUnreachable();
-  finally_environment_->Push(nullptr);
+  finally_environment_->Push(the_hole());
 }