Migrate LongJumpScope to Thread.

runtime/vm/thread.h

Index: runtime/vm/thread.h
diff --git a/runtime/vm/thread.h b/runtime/vm/thread.h
index 69cc4ecd17b2f70a429bd02bd899675a274b5496..bee3d9f35bc2a7bdbb9368bc1cb8a87acb9448bd 100644
--- a/runtime/vm/thread.h
+++ b/runtime/vm/thread.h
@@ -16,6 +16,7 @@ class HandleScope;
 class Heap;
 class InterruptableThreadState;
 class Isolate;
+class LongJumpScope;
 class Object;
 class RawBool;
 class RawObject;
@@ -201,6 +202,7 @@ class Thread {
     TimelineEventBlock* timeline_block;
     // TODO(koda): Migrate individual fields of InterruptableThreadState.
     InterruptableThreadState* thread_state;
+    LongJumpScope* long_jump_base;
 #if defined(DEBUG)
     HandleScope* top_handle_scope;
     intptr_t no_handle_scope_depth;
@@ -226,6 +228,11 @@ CACHED_CONSTANTS_LIST(DEFINE_OFFSET_METHOD)
     state_.timeline_block = block;
   }
 
+  LongJumpScope* long_jump_base() const { return state_.long_jump_base; }
+  void set_long_jump_base(LongJumpScope* value) {
+    state_.long_jump_base = value;
+  }
+
  private:
   static ThreadLocalKey thread_key_;