[webkit.UncountedLambdaCapturesChecker] Recognize nested protectedThis pattern (#126443) In WebKit, it's pretty common to capture "this" and "protectedThis" where "protectedThis" is a guardian variable of type Ref or RefPtr for "this". Furthermore, it's common for this "protectedThis" variable from being passed to an inner lambda by std::move. Recognize this pattern so that we don't emit warnings for nested inner lambdas. To recognize this pattern, we introduce a new DenseSet, ProtectedThisDecls, which contains every "protectedThis" we've recognized to our subclass of DynamicRecursiveASTVisitor. This set is now populated in "hasProtectedThis" and "declProtectsThis" uses this DenseSet to determine a given value declaration constitutes a "protectedThis" pattern or not. Because hasProtectedThis and declProtectsThis had to be moved from the checker class to the visitor class, it's now a responsibility of each caller of visitLambdaExpr to check whether a given lambda captures "this" without a "protectedThis" or not. Finally, this PR improves the code to recognize "protectedThis" pattern by allowing more nested CXXBindTemporaryExpr, CXXOperatorCallExpr, and UnaryOperator expressions.
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