Restrict GeneratePreagedPrologue to proper functions.

src/compiler.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_H_
 #define V8_COMPILER_H_
 
 #include "src/allocation.h"
 #include "src/ast/ast.h"
 #include "src/bailout-reason.h"
@@ skipping 252 matching lines @@
   bool is_splitting_enabled() const { return GetFlag(kSplittingEnabled); }
 
   void MarkAsFirstCompile() { SetFlag(kFirstCompile); }
 
   void MarkAsCompiled() { SetFlag(kFirstCompile, false); }
 
   bool is_first_compile() const { return GetFlag(kFirstCompile); }
 
   bool GeneratePreagedPrologue() const {
     // Generate a pre-aged prologue if we are optimizing for size, which
-    // will make code flushing more aggressive. The code for WASM functions
-    // cannot be flushed, so it does not make sense to age them.
+    // will make code flushing more aggressive. Only apply to Code::FUNCTION,
+    // since StaticMarkingVisitor::IsFlushable only flushes proper functions.
     return FLAG_optimize_for_size && FLAG_age_code && !will_serialize() &&
-           !is_debug() && output_code_kind_ != Code::WASM_FUNCTION;
+           !is_debug() && output_code_kind_ == Code::FUNCTION;
   }
 
   void EnsureFeedbackVector();
   Handle<TypeFeedbackVector> feedback_vector() const {
     return feedback_vector_;
   }
   void SetCode(Handle<Code> code) { code_ = code; }
 
   void SetBytecodeArray(Handle<BytecodeArray> bytecode_array) {
     bytecode_array_ = bytecode_array;
@@ skipping 432 matching lines @@
   size_t info_zone_start_allocation_size_;
   base::ElapsedTimer timer_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilationPhase);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_H_