Make number of available threads isolate-dependent and expose it to ResourceConstraints.

src/compiler.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 284 matching lines @@
 
   Handle<Foreign> object_wrapper() {
     if (object_wrapper_.is_null()) {
       object_wrapper_ =
           isolate()->factory()->NewForeign(reinterpret_cast<Address>(this));
     }
     return object_wrapper_;
   }
 
   void AbortDueToDependencyChange() {
-    ASSERT(!isolate()->optimizing_compiler_thread()->IsOptimizerThread());
+    ASSERT(!OptimizingCompilerThread::IsOptimizerThread(isolate()));
     abort_due_to_dependency_ = true;
   }
 
   bool HasAbortedDueToDependencyChange() {
-    ASSERT(!isolate()->optimizing_compiler_thread()->IsOptimizerThread());
+    ASSERT(!OptimizingCompilerThread::IsOptimizerThread(isolate()));
     return abort_due_to_dependency_;
   }
 
   void set_osr_pc_offset(uint32_t pc_offset) {
     osr_pc_offset_ = pc_offset;
   }
 
   bool HasSameOsrEntry(Handle<JSFunction> function, uint32_t pc_offset) {
     return osr_pc_offset_ == pc_offset && function.is_identical_to(closure_);
   }
@@ skipping 350 matching lines @@
   unsigned info_zone_start_allocation_size_;
   ElapsedTimer timer_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilationPhase);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_COMPILER_H_