Move no_callback_scope_depth_ and cha_ from isolate -> thread

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 6921919acfa831429c824a8e2cec7c7805687d73..00abb13659ea92ec77707cbe1db94571adcd980e 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -27,7 +27,6 @@ namespace dart {
 class ApiState;
 class BackgroundCompiler;
 class Capability;
-class CHA;
 class CodeIndexTable;
 class CompilerStats;
 class Debugger;
@@ -851,9 +850,6 @@ class Isolate : public BaseIsolate {
 
   bool compilation_allowed_;
 
-  // TODO(23153): Move this out of Isolate/Thread.
-  CHA* cha_;
-
   // Isolate list next pointer.
   Isolate* next_;