rpc: add rpc v2 chainSpec to polkadot (#2859)

The [chainSpec RPC API from the v2
spec](https://paritytech.github.io/json-rpc-interface-spec/api/chainSpec.html)
was only added to substrate-node and should be added to polkadot as well

/cc @lexnv

substrate/frame/contracts/fixtures/build.rs

@@ -105,7 +105,7 @@ fn collect_entries(contracts_dir: &Path, out_dir: &Path) -> Vec<Entry> {
 		.filter_map(|file| {
 			let path = file.expect("file exists; qed").path();
 			if path.extension().map_or(true, |ext| ext != "rs") {
-				return None;
+				return None
 			}
 
 			let entry = Entry::new(path);
@@ -307,7 +307,7 @@ fn find_workspace_root(current_dir: &Path) -> Option<PathBuf> {
 			let cargo_toml_contents =
 				std::fs::read_to_string(current_dir.join("Cargo.toml")).ok()?;
 			if cargo_toml_contents.contains("[workspace]") {
-				return Some(current_dir);
+				return Some(current_dir)
 			}
 		}
 
@@ -325,7 +325,7 @@ fn main() -> Result<()> {
 
 	let entries = collect_entries(&contracts_dir, &out_dir);
 	if entries.is_empty() {
-		return Ok(());
+		return Ok(())
 	}
 
 	let tmp_dir = tempfile::tempdir()?;

substrate/frame/support/procedural/src/construct_runtime/expand/task.rs

@@ -31,7 +31,7 @@ pub fn expand_outer_task(
 	let mut task_paths = Vec::new();
 	for decl in pallet_decls {
 		if decl.find_part("Task").is_none() {
-			continue;
+			continue
 		}
 
 		let variant_name = &decl.name;

substrate/frame/system/src/tests.rs

@@ -828,7 +828,7 @@ fn last_runtime_upgrade_spec_version_usage() {
 			// a runtime upgrade in the pipeline of being applied, you should use the spec version
 			// of this upgrade.
 			if System::last_runtime_upgrade_spec_version() > 1337 {
-				return Weight::zero();
+				return Weight::zero()
 			}
 
 			// Do the migration.