Bug 1302949 - Add a method to parse a property-value pair into a declaration block; r=Manishearth

The property may be a shorthand property in which case the declaration block
will contain the expanded longhand properties and values.

MozReview-Commit-ID: KxqlYgbIZqL

components/style/gecko_bindings/bindings.rs

@@ -847,6 +847,18 @@ extern "C" {
                                                  reference:
                                                      RawServoStyleSheetBorrowed);
 }
+extern "C" {
+    pub fn Servo_ParseProperty(property_bytes: *const u8,
+                               property_length: u32,
+                               value_bytes: *const u8,
+                               value_length: u32,
+                               base_bytes: *const u8,
+                               base_length: u32,
+                               base: *mut ThreadSafeURIHolder,
+                               referrer: *mut ThreadSafeURIHolder,
+                               principal: *mut ThreadSafePrincipalHolder)
+    -> ServoDeclarationBlockStrong;
+}
 extern "C" {
     pub fn Servo_ParseStyleAttribute(bytes: *const u8, length: u32,
                                      cache: *mut nsHTMLCSSStyleSheet)