throw out values when ${ pattern occurs

If this occurs inside of strings then it's fine but everywhere else it's
thrown out.

Technically you can set it in the value of a CSS variable, but I think
guarding against that is only needed if somebody actually runs into
problems with this.

crates/oxide/src/extractor/arbitrary_property_machine.rs

@@ -226,6 +226,11 @@ impl Machine for ArbitraryPropertyMachine<ParsingValueState> {
                 // URLs are not allowed
                 Class::Slash if start_of_value_pos == cursor.pos => return self.restart(),
 
+                // String interpolation-like syntax is not allowed. E.g.: `[${x}]`
+                Class::Dollar if matches!(cursor.next.into(), Class::OpenCurly) => {
+                    return self.restart()
+                }
+
                 // Everything else is valid
                 _ => cursor.advance(),
             };
@@ -276,6 +281,9 @@ enum Class {
     #[bytes(b'-')]
     Dash,
 
+    #[bytes(b'$')]
+    Dollar,
+
     #[bytes_range(b'a'..=b'z')]
     AlphaLower,
 

crates/oxide/src/extractor/arbitrary_value_machine.rs

@@ -95,6 +95,11 @@ impl Machine for ArbitraryValueMachine {
                 // Any kind of whitespace is not allowed
                 Class::Whitespace => return self.restart(),
 
+                // String interpolation-like syntax is not allowed. E.g.: `[${x}]`
+                Class::Dollar if matches!(cursor.next.into(), Class::OpenCurly) => {
+                    return self.restart()
+                }
+
                 // Everything else is valid
                 _ => cursor.advance(),
             };
@@ -133,6 +138,9 @@ enum Class {
     #[bytes(b' ', b'\t', b'\n', b'\r', b'\x0C')]
     Whitespace,
 
+    #[bytes(b'$')]
+    Dollar,
+
     #[fallback]
     Other,
 }

crates/oxide/src/extractor/arbitrary_variable_machine.rs

@@ -252,6 +252,11 @@ impl Machine for ArbitraryVariableMachine<ParsingFallbackState> {
                 // Any kind of whitespace is not allowed
                 Class::Whitespace => return self.restart(),
 
+                // String interpolation-like syntax is not allowed. E.g.: `[${x}]`
+                Class::Dollar if matches!(cursor.next.into(), Class::OpenCurly) => {
+                    return self.restart()
+                }
+
                 // Everything else is valid
                 _ => cursor.advance(),
             };
@@ -284,6 +289,9 @@ enum Class {
     #[bytes(b'.')]
     Dot,
 
+    #[bytes(b'$')]
+    Dollar,
+
     #[bytes(b'\\')]
     Escape,