refactor(isBtcAddress): get rid of unnecessary if statement and comment (#2132)

* there is no need to do a check before, which RegExp use
* refactored version also is bit faster as well, according to Benchmark.js tests I did

Author: pano9000

src/lib/isBtcAddress.js

@@ -1,14 +1,9 @@
 import assertString from './util/assertString';
 
-// supports Bech32 addresses
 const bech32 = /^(bc1)[a-z0-9]{25,39}$/;
 const base58 = /^(1|3)[A-HJ-NP-Za-km-z1-9]{25,39}$/;
 
 export default function isBtcAddress(str) {
   assertString(str);
-  // check for bech32
-  if (str.startsWith('bc1')) {
-    return bech32.test(str);
-  }
-  return base58.test(str);
+  return bech32.test(str) || base58.test(str);
 }