Include only stuff you need, part 3: includes in isolate.h.

src/isolate.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_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <memory>
 #include <queue>
-#include <set>
 
 #include "include/v8-debug.h"
 #include "src/allocation.h"
-#include "src/assert-scope.h"
-#include "src/base/accounting-allocator.h"
 #include "src/base/atomicops.h"
-#include "src/base/hashmap.h"
 #include "src/builtins/builtins.h"
-#include "src/cancelable-task.h"
-#include "src/compiler-dispatcher/optimizing-compile-dispatcher.h"
 #include "src/contexts.h"
 #include "src/date.h"
 #include "src/execution.h"
 #include "src/frames.h"
 #include "src/futex-emulation.h"
 #include "src/global-handles.h"
 #include "src/handles.h"
 #include "src/heap/heap.h"
 #include "src/messages.h"
 #include "src/regexp/regexp-stack.h"
-#include "src/runtime-profiler.h"
 #include "src/runtime/runtime.h"
 #include "src/tracing/trace-event.h"
 #include "src/zone.h"
 
 namespace v8 {
 
 namespace base {
+class AccountingAllocator;
 class RandomNumberGenerator;
 }
 
 namespace internal {
 
 class BasicBlockProfiler;
 class Bootstrapper;
+class CancelableTaskManager;
 class CallInterfaceDescriptorData;
 class CodeAgingHelper;
 class CodeEventDispatcher;
 class CodeGenerator;
 class CodeRange;
 class CodeStubDescriptor;
 class CodeTracer;
 class CompilationCache;
 class CompilationStatistics;
 class ContextSlotCache;
 class Counters;
 class CpuFeatures;
 class CpuProfiler;
 class DeoptimizerData;
 class Deserializer;
 class EmptyStatement;
 class ExternalCallbackScope;
 class ExternalReferenceTable;
 class Factory;
 class HandleScopeImplementer;
 class HeapProfiler;
 class HStatistics;
 class HTracer;
 class InlineRuntimeFunctionsTable;
 class InnerPointerToCodeCache;
 class Logger;
 class MaterializedObjectStore;
+class OptimizingCompileDispatcher;
 class RegExpStack;
+class RuntimeProfiler;
 class SaveContext;
 class StatsTable;
 class StringTracker;
 class StubCache;
 class SweeperThread;
 class ThreadManager;
 class ThreadState;
 class ThreadVisitor;  // Defined in v8threads.h
 class UnicodeCache;
 template <StateTag Tag> class VMState;
@@ skipping 1593 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_