Fix use of history timers in background threads.

src/compiler/wasm-compiler.h

Index: src/compiler/wasm-compiler.h
diff --git a/src/compiler/wasm-compiler.h b/src/compiler/wasm-compiler.h
index e2ba575507b80a3ef3f38b854a1badd3cfe2f3b7..37d8ac6ddeab9a827790748e6c2ef025c123db64 100644
--- a/src/compiler/wasm-compiler.h
+++ b/src/compiler/wasm-compiler.h
@@ -48,10 +48,9 @@ namespace compiler {
 class WasmCompilationUnit final {
  public:
   WasmCompilationUnit(Isolate* isolate, wasm::ModuleBytesEnv* module_env,
-                      const wasm::WasmFunction* function, bool is_sync = true);
+                      const wasm::WasmFunction* function);
   WasmCompilationUnit(Isolate* isolate, wasm::ModuleEnv* module_env,
-                      wasm::FunctionBody body, wasm::WasmName name, int index,
-                      bool is_sync = true);
+                      wasm::FunctionBody body, wasm::WasmName name, int index);
 
   Zone* graph_zone() { return graph_zone_.get(); }
   int func_index() const { return func_index_; }
@@ -72,7 +71,6 @@ class WasmCompilationUnit final {
   wasm::ModuleEnv* module_env_;
   wasm::FunctionBody func_body_;
   wasm::WasmName func_name_;
-  bool is_sync_;
   // The graph zone is deallocated at the end of ExecuteCompilation.
   std::unique_ptr<Zone> graph_zone_;
   JSGraph* jsgraph_;
@@ -89,8 +87,6 @@ class WasmCompilationUnit final {
       protected_instructions_;  // Instructions that are protected by the signal
                                 // handler.
 
-  void ExecuteCompilationInternal();
-
   DISALLOW_COPY_AND_ASSIGN(WasmCompilationUnit);
 };