Auto merge of #18946 - cynicaldevil:update-h5e, r=nox

Update h5e version

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tests/unit/style/Cargo.toml

@@ -14,7 +14,7 @@ byteorder = "1.0"
 app_units = "0.5"
 cssparser = "0.22.0"
 euclid = "0.15"
-html5ever = "0.20"
+html5ever = "0.21"
 parking_lot = "0.4"
 rayon = "0.8"
 rustc-serialize = "0.3"