React immediately to memory pressure on foreground threads

src/execution.h

 // Copyright 2014 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_EXECUTION_H_
 #define V8_EXECUTION_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
+#include "src/globals.h"
 #include "src/utils.h"
 
 namespace v8 {
 namespace internal {
 
 template <typename T>
 class Handle;
 
 class Execution final : public AllStatic {
  public:
@@ skipping 36 matching lines @@
 };
 
 
 class ExecutionAccess;
 class PostponeInterruptsScope;
 
 
 // StackGuard contains the handling of the limits that are used to limit the
 // number of nested invocations of JavaScript and the stack size used in each
 // invocation.
-class StackGuard final {
+class V8_EXPORT_PRIVATE StackGuard final {
  public:
   // Pass the address beyond which the stack should not grow.  The stack
   // is assumed to grow downwards.
   void SetStackLimit(uintptr_t limit);
 
   // The simulator uses a separate JS stack. Limits on the JS stack might have
   // to be adjusted in order to reflect overflows of the C stack, because we
   // cannot rely on the interleaving of frames on the simulator.
   void AdjustStackLimitForSimulator();
 
@@ skipping 147 matching lines @@
   friend class StackLimitCheck;
   friend class PostponeInterruptsScope;
 
   DISALLOW_COPY_AND_ASSIGN(StackGuard);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_EXECUTION_H_