[naga] Simplify function names and comments.

Remove the phrase "zero-based" from comments and function names. Now
that there is no mix of zero-based and one-based indices, there's no
need to call out the distinction.

naga/src/arena.rs

@@ -89,7 +89,7 @@ impl<T> Handle<T> {
         }
     }
 
-    /// Returns the zero-based index of this handle.
+    /// Returns the index of this handle.
     pub const fn index(self) -> usize {
         self.index.get() as usize
     }
@@ -221,13 +221,13 @@ impl<T> Range<T> {
         }
     }
 
-    /// Return the zero-based index range covered by `self`.
-    pub fn zero_based_index_range(&self) -> ops::Range<u32> {
+    /// Return the index range covered by `self`.
+    pub fn index_range(&self) -> ops::Range<u32> {
         self.inner.clone()
     }
 
-    /// Construct a `Range` that covers the zero-based indices in `inner`.
-    pub fn from_zero_based_index_range(inner: ops::Range<u32>, arena: &Arena<T>) -> Self {
+    /// Construct a `Range` that covers the indices in `inner`.
+    pub fn from_index_range(inner: ops::Range<u32>, arena: &Arena<T>) -> Self {
         // Since `inner` is a `Range<u32>`, we only need to check that
         // the start and end are well-ordered, and that the end fits
         // within `arena`.

naga/src/compact/handle_set_map.rs

@@ -137,7 +137,7 @@ impl<T: 'static> HandleMap<T> {
     ///
     /// Use `compacted_arena` to bounds-check the result.
     pub fn adjust_range(&self, range: &mut Range<T>, compacted_arena: &Arena<T>) {
-        let mut index_range = range.zero_based_index_range();
+        let mut index_range = range.index_range();
         let compacted;
         if let Some(first) = index_range.find_map(|i| self.new_index[i as usize]) {
             // The first call to `find_map` mutated `index_range` to hold the
@@ -155,6 +155,6 @@ impl<T: 'static> HandleMap<T> {
         } else {
             compacted = 0..0;
         };
-        *range = Range::from_zero_based_index_range(compacted, compacted_arena);
+        *range = Range::from_index_range(compacted, compacted_arena);
     }
 }