Cleanup (#162)

* Remove unnecessary references

* Shorten expressions

* Remove unnecessary reference

* Simplify expression

* Fix formatting

src/stack_height/max_height.rs

@@ -80,10 +80,7 @@ impl Stack {
 	/// Returns `Err` if the control stack is empty.
 	fn pop_frame(&mut self) -> Result<Frame, Error> {
 		trace!(target: "max_height", "pop_frame: {:?}", self.control_stack.last());
-		Ok(self
-			.control_stack
-			.pop()
-			.ok_or_else(|| Error("stack must be non-empty".into()))?)
+		self.control_stack.pop().ok_or_else(|| Error("stack must be non-empty".into()))
 	}
 
 	/// Truncate the height of value stack to the specified height.

src/stack_height/mod.rs

@@ -176,7 +176,7 @@ fn compute_stack_costs(module: &elements::Module) -> Result<Vec<u32>, Error> {
 				// We can't calculate stack_cost of the import functions.
 				Ok(0)
 			} else {
-				compute_stack_cost(func_idx as u32, &module)
+				compute_stack_cost(func_idx as u32, module)
 			}
 		})
 		.collect()