add unicode_xid, test

Cargo.toml

@@ -18,7 +18,6 @@ categories = [ "no-std", "embedded", "parser-implementations" ]
 
 [dependencies]
 num-traits = { version = "0.2.11", default-features = false }
-unicode-xid = "0.2.1"
 
 [features]
 #default = ["unchecked", "sync", "no_optimize", "no_float", "only_i32", "no_index", "no_object", "no_function", "no_module"]
@@ -35,6 +34,7 @@ no_object = []      # no custom objects
 no_function = []    # no script-defined functions
 no_module = []      # no modules
 internals = []      # expose internal data structures
+unicode-xid-ident = ["unicode-xid"]  # allow unicode-xid for identifiers.
 
 # compiling for no-std
 no_std = [ "num-traits/libm", "hashbrown", "core-error", "libm", "ahash" ]
@@ -74,6 +74,11 @@ default_features = false
 features = ["derive", "alloc"]
 optional = true
 
+[dependencies.unicode-xid]
+version = "0.2.1"
+default_features = false
+optional = true
+
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 instant= { version = "0.1.4", features = ["wasm-bindgen"] } # WASM implementation of std::time::Instant