Perform clippy and remove a lot of little things

core/engine/src/builtins/array_buffer/mod.rs

@@ -712,8 +712,6 @@ impl ArrayBuffer {
             };
 
             // 26. Perform CopyDataBlockBytes(toBuf, 0, fromBuf, first, newLen).
-            let first = first;
-            let new_len = new_len;
             to_buf[..new_len].copy_from_slice(&from_buf[first..first + new_len]);
         }
 
@@ -933,10 +931,6 @@ pub(crate) fn create_byte_data_block(
 
     // 1. Let db be a new Data Block value consisting of size bytes. If it is impossible to
     //    create such a Data Block, throw a RangeError exception.
-    let alloc_size = alloc_size.try_into().map_err(|e| {
-        JsNativeError::range().with_message(format!("couldn't allocate the data block: {e}"))
-    })?;
-
     let mut data_block = Vec::new();
     data_block.try_reserve_exact(alloc_size).map_err(|e| {
         JsNativeError::range().with_message(format!("couldn't allocate the data block: {e}"))

core/engine/src/builtins/array_buffer/shared.rs

@@ -336,7 +336,6 @@ impl SharedArrayBuffer {
                 )
                 .into());
         }
-        let new_byte_len = new_byte_len;
 
         // If we used let-else above to avoid the expect, we would carry a borrow through the `to_index`
         // call, which could mutably borrow. Another alternative would be to clone the whole
@@ -448,8 +447,6 @@ impl SharedArrayBuffer {
                     .into());
             }
 
-            let new_len = new_len;
-
             // 20. Let fromBuf be O.[[ArrayBufferData]].
             let from_buf = &buf.bytes_with_len(len)[first..];
 
@@ -563,10 +560,6 @@ pub(crate) fn create_shared_byte_data_block(
 
     // 1. Let db be a new Shared Data Block value consisting of size bytes. If it is impossible to
     //    create such a Shared Data Block, throw a RangeError exception.
-    let size = size.try_into().map_err(|e| {
-        JsNativeError::range().with_message(format!("couldn't allocate the data block: {e}"))
-    })?;
-
     if size == 0 {
         // Must ensure we don't allocate a zero-sized buffer.
         return Ok(Box::default());

core/engine/src/builtins/typed_array/builtin.rs

@@ -1816,9 +1816,6 @@ impl BuiltinTypedArray {
         // 19. If SameValue(srcBuffer, targetBuffer) is true or sameSharedArrayBuffer is true, then
         let src_byte_index = if BufferObject::equals(&src_buf_obj, &target_buf_obj) {
             // a. Let srcByteLength be source.[[ByteLength]].
-            let src_byte_offset = src_byte_offset;
-            let src_byte_length = src_byte_length;
-
             let s = {
                 let slice = src_buf_obj.as_buffer();
                 let slice = slice
@@ -1859,8 +1856,6 @@ impl BuiltinTypedArray {
 
         // 24. If srcType is the same as targetType, then
         if src_type == target_type {
-            let src_byte_index = src_byte_index;
-            let target_byte_index = target_byte_index;
             let byte_count = target_element_size * src_length;
 
             // a. NOTE: If srcType and targetType are the same, the transfer must be performed in a manner that preserves the bit-level encoding of the source data.
@@ -2895,7 +2890,6 @@ impl BuiltinTypedArray {
                         .into());
                 }
 
-                let src_element_size = src_element_size;
                 let target_element_size = element_size;
 
                 // c. Let srcByteIndex be srcByteOffset.

core/engine/src/object/builtins/jsdataview.rs

@@ -109,7 +109,7 @@ impl JsDataView {
 
         // 11. If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
         // 12. Set bufferByteLength to ArrayBufferByteLength(buffer, seq-cst).
-        let Some(buf_byte_len) = buffer.borrow().data.bytes().map(|s| s.len()) else {
+        let Some(buf_byte_len) = buffer.borrow().data.bytes().map(<[u8]>::len) else {
             return Err(JsNativeError::typ()
                 .with_message("ArrayBuffer is detached")
                 .into());

core/engine/src/value/conversions/try_from_js.rs

@@ -94,14 +94,6 @@ where
         let length = object
             .get(js_string!("length"), context)?
             .to_length(context)?;
-        let length = match usize::try_from(length) {
-            Ok(length) => length,
-            Err(e) => {
-                return Err(JsNativeError::typ()
-                    .with_message(format!("could not convert length to usize: {e}"))
-                    .into());
-            }
-        };
         let mut vec = Vec::with_capacity(length);
         for i in 0..length {
             let value = object.get(i, context)?;