Fixes 139-Word-Break.js

Fixes issue with the previous word break code. It fails for test case 
"leetcode"
["leet","code", "de"]

Author: SuryaL

javascript/139-Word-Break.js

@@ -1,17 +1,15 @@
 let wordBreak = function (s, wordDict) {
-    let dp = new Array(s.length + 1);
-    dp.fill(false);
+    let dp = new Array(s.length + 1).fill(false);
     dp[s.length] = true;
 
-    let word = '';
     for (let i = s.length - 1; i >= 0; i--) {
-        word = s[i] + word;
-
-        if (wordDict.includes(word) && i + word.length < dp.length) {
-            dp[i] = dp[i + word.length];
-            word = '';
-        } else {
-            dp[i] = false;
+        for(let w of wordDict){
+            if (i + w.length <= s.length && s.substring(i, i + w.length) === w) {
+                dp[i] = dp[i + w.length];
+            }
+            if(dp[i]){
+                break;
+            }
         }
     }