deps: Update mozjs to 0.15.7 (servo#43618)

This mainly includes:

- servo/mozjs#717
- servo/mozjs#725

Testing: Covered by existing tests.

Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>

Author: jschwe

Cargo.lock

@@ -108,7 +108,7 @@ imsz = "0.4"
 indexmap = { version = "2.11.4", features = ["std"] }
 ipc-channel = "0.21"
 itertools = "0.14"
-js = { package = "mozjs", version = "=0.15.5", default-features = false, features = ["libz-sys", "intl"] }
+js = { package = "mozjs", version = "=0.15.7", default-features = false, features = ["libz-sys", "intl"] }
 keyboard-types = { version = "0.8.3", features = ["serde", "webdriver"] }
 kurbo = { version = "0.12", features = ["euclid"] }
 libc = "0.2"