Merge pull request #3250 from MetaMask/i#3136

fix - hex prefix estimatedGas on txMeta

app/scripts/lib/tx-gas-utils.js

@@ -4,6 +4,7 @@ const {
   BnMultiplyByFraction,
   bnToHex,
 } = require('./util')
+const addHexPrefix = require('ethereumjs-util').addHexPrefix
 const SIMPLE_GAS_COST = '0x5208' // Hex for 21000, cost of a simple send.
 
 /*
@@ -68,7 +69,7 @@ module.exports = class TxGasUtil {
   }
 
   setTxGas (txMeta, blockGasLimitHex, estimatedGasHex) {
-    txMeta.estimatedGas = estimatedGasHex
+    txMeta.estimatedGas = addHexPrefix(estimatedGasHex)
     const txParams = txMeta.txParams
 
     // if gasLimit was specified and doesnt OOG,