Remove a bunch of Isolate::UncheckedCurrent calls

src/isolate.cc

 // 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.
 
 #include <stdlib.h>
 
 #include "src/v8.h"
 
 #include "src/ast.h"
 #include "src/base/platform/platform.h"
@@ skipping 2035 matching lines @@
       ASSERT(entry_stack_ != NULL);
       ASSERT(entry_stack_->previous_thread_data == NULL ||
              entry_stack_->previous_thread_data->thread_id().Equals(
                  ThreadId::Current()));
       // Same thread re-enters the isolate, no need to re-init anything.
       entry_stack_->entry_count++;
       return;
     }
   }
 
-  // Threads can have default isolate set into TLS as Current but not yet have
-  // PerIsolateThreadData for it, as it requires more advanced phase of the
-  // initialization. For example, a thread might be the one that system used for
-  // static initializers - in this case the default isolate is set in TLS but
-  // the thread did not yet Enter the isolate. If PerisolateThreadData is not
-  // there, use the isolate set in TLS.
-  if (current_isolate == NULL) {
-    current_isolate = Isolate::UncheckedCurrent();
-  }
-
   PerIsolateThreadData* data = FindOrAllocatePerThreadDataForThisThread();
   ASSERT(data != NULL);
   ASSERT(data->isolate_ == this);
 
   EntryStackItem* item = new EntryStackItem(current_data,
                                             current_isolate,
                                             entry_stack_);
   entry_stack_ = item;
 
   SetIsolateThreadLocals(this, data);
@@ skipping 303 matching lines @@
   if (prev_ && prev_->Intercept(flag)) return true;
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 } }  // namespace v8::internal