[llvm] [VPlan] Verify dominance for incoming values of phi-like recipes. (PR #124838)

[via llvm-commits]

================
@@ -3283,6 +3295,43 @@ class VPScalarIVStepsRecipe : public VPRecipeWithIRFlags,
   }
 };
 
+/// Casting from VPRecipeBase -> VPPhiAccessors is supported for all recipe
+/// types implementing VPPhiAccessors.
----------------
ayalz wrote:

```suggestion
/// types implementing VPPhiAccessors. CastIsPossible is used by isa.
```

https://github.com/llvm/llvm-project/pull/124838