Max code size on Kovan (#8067)

* Enable code size limit on kovan

* Fix formatting.

json/src/spec/params.rs

@@ -113,6 +113,9 @@ pub struct Params {
 	/// See main EthashParams docs.
 	#[serde(rename="maxCodeSize")]
 	pub max_code_size: Option<Uint>,
+	/// See main EthashParams docs.
+	#[serde(rename="maxCodeSizeTransition")]
+	pub max_code_size_transition: Option<Uint>,
 	/// Transaction permission contract address.
 	#[serde(rename="transactionPermissionContract")]
 	pub transaction_permission_contract: Option<Address>,