Run both Node and browser tests on distribution version

.travis.yml

@@ -1,5 +1,6 @@
 language: node_js
 node_js:
+  - "4"
   - "6"
   - "8"
 env:

package.json

@@ -10,10 +10,10 @@
     "coverage": "istanbul cover _mocha",
     "coveralls": "npm run coverage && coveralls <coverage/lcov.info",
     "lint": "standard",
-    "prepublishOnly": "npm run lint && npm run test && npm run build:dist",
+    "prepublishOnly": "npm run lint && npm run build:dist && npm run test",
     "test": "npm run test:node && npm run test:browser",
-    "test:browser": "karma start karma.conf.js",
-    "test:node": "istanbul test mocha -- --reporter spec",
+    "test:browser": "npm run build:dist && karma start karma.conf.js",
+    "test:node": "npm run build:dist && istanbul test mocha -- --reporter spec",
     "build:dist": "babel index.js --source-root ./ -d ./dist",
     "build:docs": "documentation build ./index.js --github --sort-order='alpha' -f md > ./docs/index.md"
   },

test/defineFields.js

@@ -1,5 +1,5 @@
 var assert = require('assert')
-var ethUtil = require('../index.js')
+var ethUtil = require('../dist/index.js')
 
 describe('define', function () {
   const fields = [{

test/index.js

@@ -1,5 +1,5 @@
 var assert = require('assert')
-var ethUtils = require('../index.js')
+var ethUtils = require('../dist/index.js')
 var BN = require('bn.js')
 
 describe('zeros function', function () {