[Interpreter] Remove unused ControlScope::RethrowAccumulator.

Bug: 
Change-Id: I77915d33e427f00f42fb61ed0ba903e43d737180
Reviewed-on: https://chromium-review.googlesource.com/565417Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46524}

src/interpreter/bytecode-generator.cc

@@ -104,7 +104,6 @@ class BytecodeGenerator::ControlScope BASE_EMBEDDED {
   void Continue(Statement* stmt) { PerformCommand(CMD_CONTINUE, stmt); }
   void ReturnAccumulator() { PerformCommand(CMD_RETURN, nullptr); }
   void AsyncReturnAccumulator() { PerformCommand(CMD_ASYNC_RETURN, nullptr); }
-  void ReThrowAccumulator() { PerformCommand(CMD_RETHROW, nullptr); }
 
   class DeferredCommands;