[isolate] Remove unused exception handle

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>
@@ skipping 404 matching lines @@
   V(ExternalReferenceRedirectorPointer*, external_reference_redirector,       \
     nullptr)                                                                  \
   /* State for Relocatable. */                                                \
   V(Relocatable*, relocatable_top, nullptr)                                   \
   V(DebugObjectCache*, string_stream_debug_object_cache, nullptr)             \
   V(Object*, string_stream_current_security_token, nullptr)                   \
   V(ExternalReferenceTable*, external_reference_table, nullptr)               \
   V(intptr_t*, api_external_references, nullptr)                              \
   V(base::HashMap*, external_reference_map, nullptr)                          \
   V(base::HashMap*, root_index_map, nullptr)                                  \
-  V(int, pending_microtask_count, 0)                                          \
+  V(int, pending_microtask_count, 1)                                          \
   V(HStatistics*, hstatistics, nullptr)                                       \
   V(CompilationStatistics*, turbo_statistics, nullptr)                        \
   V(HTracer*, htracer, nullptr)                                               \
   V(CodeTracer*, code_tracer, nullptr)                                        \
   V(bool, fp_stubs_generated, false)                                          \
   V(uint32_t, per_isolate_assert_data, 0xFFFFFFFFu)                           \
   V(PromiseRejectCallback, promise_reject_callback, nullptr)                  \
   V(const v8::StartupData*, snapshot_blob, nullptr)                           \
   V(int, code_and_metadata_size, 0)                                           \
   V(int, bytecode_and_metadata_size, 0)                                       \
@@ skipping 1241 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_