style: Add bindings for LengthPercentage, and use it for text-indent.

Which is the only property that uses LengthPercentage alone.

Differential Revision: https://phabricator.services.mozilla.com/D17737

components/style/cbindgen.toml

@@ -7,6 +7,8 @@ autogen_warning = """/* DO NOT MODIFY THIS MANUALLY! This file was generated usi
  *      a. Alternatively, you can clone `https://github.com/eqrion/cbindgen` and use a tagged release
  *   2. Run `rustup run nightly cbindgen toolkit/library/rust/ --lockfile Cargo.lock --crate style -o layout/style/ServoStyleConsts.h`
  */
+#include "nsCoord.h"
+#include "Units.h"
 class nsAtom;
 namespace mozilla {
   namespace css {
@@ -27,7 +29,7 @@ namespaces = ["mozilla"]
 
 [parse]
 parse_deps = true
-include = ["cssparser"]
+include = ["cssparser", "style_traits"]
 
 [struct]
 derive_eq = true
@@ -71,3 +73,20 @@ include = [
   "LengthPercentage",
 ]
 item_types = ["enums", "structs", "typedefs"]
+
+[export.body]
+"LengthPercentage" = """
+  // Defined in nsStyleCoord.h
+  static inline StyleLengthPercentage Zero();
+  inline bool HasPercent() const;
+  inline bool ConvertsToLength() const;
+  inline nscoord ToLength() const;
+  inline bool ConvertsToPercentage() const;
+  inline float ToPercentage() const;
+  inline CSSCoord LengthInCSSPixels() const;
+  inline float Percentage() const;
+  inline CSSCoord ResolveToCSSPixels(CSSCoord aPercentageBasisInCSSPixels) const;
+  template<typename T> inline CSSCoord ResolveToCSSPixelsWith(T aPercentageGetter) const;
+  inline nscoord Resolve(nscoord aPercentageBasis) const;
+  template<typename T> inline nscoord ResolveWith(T aPercentageGetter) const;
+"""

components/style/properties/gecko.mako.rs

@@ -1389,7 +1389,7 @@ impl Clone for ${style_struct.gecko_struct_name} {
         "FlexBasis": impl_style_coord,
         "Length": impl_absolute_length,
         "LengthOrNormal": impl_style_coord,
-        "LengthPercentage": impl_style_coord,
+        "LengthPercentage": impl_simple,
         "LengthPercentageOrAuto": impl_style_coord,
         "LengthPercentageOrNone": impl_style_coord,
         "MaxLength": impl_style_coord,

components/style/values/computed/length.rs

@@ -73,11 +73,12 @@ impl ToComputedValue for specified::Length {
 /// https://drafts.csswg.org/css-values-4/#typedef-length-percentage
 #[allow(missing_docs)]
 #[derive(Clone, Copy, Debug, MallocSizeOf, ToAnimatedZero)]
+#[repr(C)]
 pub struct LengthPercentage {
-    #[animation(constant)]
-    pub clamping_mode: AllowedNumericType,
     length: Length,
     percentage: Percentage,
+    #[animation(constant)]
+    pub clamping_mode: AllowedNumericType,
     /// Whether we specified a percentage or not.
     #[animation(constant)]
     pub has_percentage: bool,
@@ -678,6 +679,7 @@ impl NonNegativeLengthPercentage {
     ToAnimatedValue,
     ToAnimatedZero,
 )]
+#[repr(C)]
 pub struct CSSPixelLength(CSSFloat);
 
 impl CSSPixelLength {