[clang] [clang][coverage] fixing "if constexpr" and "if consteval" coverage report (PR #77214)

[Jessica Paquette via cfe-commits]

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@@ -7741,6 +7745,10 @@ TreeTransform<Derived>::TransformIfStmt(IfStmt *S) {
     Else = getDerived().TransformStmt(S->getElse());
     if (Else.isInvalid())
       return StmtError();
+  } else if (S->getElse() && ConstexprConditionValue &&
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ornata wrote:

Could you add a comment similar to the one in the `else` above?

https://github.com/llvm/llvm-project/pull/77214