Fix lots of typos.

eth2/utils/cached_tree_hash/src/btree_overlay.rs

@@ -64,7 +64,7 @@ pub struct BTreeOverlay {
 }
 
 impl BTreeOverlay {
-    /// Instantiates a new instance for `item`, where it's first chunk is `inital_offset` and has
+    /// Instantiates a new instance for `item`, where it's first chunk is `initial_offset` and has
     /// the specified `depth`.
     pub fn new<T>(item: &T, initial_offset: usize, depth: usize) -> Self
     where

eth2/utils/cached_tree_hash/src/impls/vec.rs

@@ -201,7 +201,7 @@ pub fn update_tree_hash_cache<T: CachedTreeHash>(
 
                         cache.chunk_index = new.end;
                     }
-                    // The list has been lengthened and this is a new item that was prevously a
+                    // The list has been lengthened and this is a new item that was previously a
                     // padding item.
                     //
                     // Splice the tree for the new item over the padding chunk.
@@ -268,7 +268,7 @@ pub fn update_tree_hash_cache<T: CachedTreeHash>(
                     // This leaf was padding in both lists, there's nothing to do.
                     (LeafNode::Padding, LeafNode::Padding) => (),
                     // As we are looping through the larger of the lists of leaf nodes, it should
-                    // be impossible for either leaf to be non-existant.
+                    // be impossible for either leaf to be non-existent.
                     (LeafNode::DoesNotExist, LeafNode::DoesNotExist) => unreachable!(),
                 }
             }

eth2/utils/cached_tree_hash/src/tree_hash_cache.rs

@@ -139,7 +139,7 @@ impl TreeHashCache {
     }
 
     /// Instantiate a new cache from the pre-built `bytes` where each `self.chunk_modified` will be
-    /// set to `intitial_modified_state`.
+    /// set to `initial_modified_state`.
     ///
     /// Note: `bytes.len()` must be a multiple of 32
     pub fn from_bytes(