Rollup merge of #117143 - estebank:issue-117080, r=wesleywiser

Avoid unbounded O(n^2) when parsing nested type args

When encountering code like `f::<f::<f::<f::<f::<f::<f::<f::<...` with unmatched closing angle brackets, add a linear check that avoids the exponential behavior of the parse recovery mechanism.

Fix https://github.com/rust-lang/rust/issues/117080, fix https://github.com/rust-lang/rust/issues/115414.