Make many functions const

The point is to set up repeated components or boilerplate before their
use sites.

The majority of these make sense as `const`. However, some functions
such as those regarding state may not make sense as `const`.

native/src/layout/limits.rs

@@ -20,7 +20,7 @@ impl Limits {
     ///
     /// [`Limits`]: struct.Limits.html
     /// [`Size`]: ../struct.Size.html
-    pub fn new(min: Size, max: Size) -> Limits {
+    pub const fn new(min: Size, max: Size) -> Limits {
         Limits {
             min,
             max,
@@ -32,7 +32,7 @@ impl Limits {
     ///
     /// [`Limits`]: struct.Limits.html
     /// [`Size`]: ../struct.Size.html
-    pub fn min(&self) -> Size {
+    pub const fn min(&self) -> Size {
         self.min
     }
 
@@ -40,7 +40,7 @@ impl Limits {
     ///
     /// [`Limits`]: struct.Limits.html
     /// [`Size`]: ../struct.Size.html
-    pub fn max(&self) -> Size {
+    pub const fn max(&self) -> Size {
         self.max
     }
 

native/src/layout/node.rs

@@ -12,7 +12,7 @@ impl Node {
     ///
     /// [`Node`]: struct.Node.html
     /// [`Size`]: ../struct.Size.html
-    pub fn new(size: Size) -> Self {
+    pub const fn new(size: Size) -> Self {
         Self::with_children(size, Vec::new())
     }
 
@@ -20,7 +20,7 @@ impl Node {
     ///
     /// [`Node`]: struct.Node.html
     /// [`Size`]: ../struct.Size.html
-    pub fn with_children(size: Size, children: Vec<Node>) -> Self {
+    pub const fn with_children(size: Size, children: Vec<Node>) -> Self {
         Node {
             bounds: Rectangle {
                 x: 0.0,
@@ -36,14 +36,14 @@ impl Node {
     ///
     /// [`Node`]: struct.Node.html
     /// [`Size`]: ../struct.Size.html
-    pub fn size(&self) -> Size {
+    pub const fn size(&self) -> Size {
         Size::new(self.bounds.width, self.bounds.height)
     }
 
     /// Returns the bounds of the [`Node`].
     ///
     /// [`Node`]: struct.Node.html
-    pub fn bounds(&self) -> Rectangle {
+    pub const fn bounds(&self) -> Rectangle {
         self.bounds
     }