Fixed work spells with ..NOT_BREAK_STEALTH and without ..NO_INITIAL_A…

…GGRO

* Target don't must lost stealth at hit by NOT_BREAK_STEALTH spell also.
* Target don't must aggro at hit not NO_INITIAL_AGGRO spell
  if caster still not detected by aggro. This possoble in case when cast not remove
  stealth (spell have NOT_BREAK_STEALTH)
* This fixed spell 921 wrong lost stealth at success and possible some other spells.

(backported from commit f73a788)

src/game/Spell.cpp

@@ -1037,14 +1037,25 @@ void Spell::DoSpellHitOnUnit(Unit *unit, const uint32 effectMask)
                 return;
             }
 
-            unit->RemoveSpellsCausingAura(SPELL_AURA_MOD_STEALTH);
+            // not break stealth by cast targeting
+            if (!(m_spellInfo->AttributesEx & SPELL_ATTR_EX_NOT_BREAK_STEALTH))
+                unit->RemoveSpellsCausingAura(SPELL_AURA_MOD_STEALTH);
 
-            if( !(m_spellInfo->AttributesEx & SPELL_ATTR_EX_NO_INITIAL_AGGRO) )
+            // can cause back attack (if detected)
+            if (!(m_spellInfo->AttributesEx & SPELL_ATTR_EX_NO_INITIAL_AGGRO) &&
+                m_caster->isVisibleForOrDetect(unit,false)) // stealth removed at Spell::cast if spell break it
             {
-                if(!unit->IsStandState() && !unit->hasUnitState(UNIT_STAT_STUNNED))
+                // use speedup check to avoid re-remove after above lines
+                if (m_spellInfo->AttributesEx & SPELL_ATTR_EX_NOT_BREAK_STEALTH)
+                    unit->RemoveSpellsCausingAura(SPELL_AURA_MOD_STEALTH);
+
+                // caster can be detected but have stealth aura
+                m_caster->RemoveSpellsCausingAura(SPELL_AURA_MOD_STEALTH);
+
+                if (!unit->IsStandState() && !unit->hasUnitState(UNIT_STAT_STUNNED))
                     unit->SetStandState(UNIT_STAND_STATE_STAND);
 
-                if(!unit->isInCombat() && unit->GetTypeId() != TYPEID_PLAYER && ((Creature*)unit)->AI())
+                if (!unit->isInCombat() && unit->GetTypeId() != TYPEID_PLAYER && ((Creature*)unit)->AI())
                     ((Creature*)unit)->AI()->AttackedBy(m_caster);
 
                 unit->AddThreat(m_caster, 0.0f);