fix(#1237): polyfill android Map.putIfAbsent

Remove usage of putIfAbsent() in the Hashmap class. This method does not exist on many old Android releases and there's no real downside to removing it.

Fixes #1237

src/org/mozilla/javascript/Hashtable.java

@@ -121,9 +121,10 @@ public int size() {
 
     public void put(Object key, Object value) {
         final Entry nv = new Entry(key, value);
-        final Entry ev = map.putIfAbsent(nv, nv);
-        if (ev == null) {
+
+        if (!map.containsKey(nv)) {
             // New value -- insert to end of doubly-linked list
+            map.put(nv, nv);
             if (first == null) {
                 first = last = nv;
             } else {
@@ -133,7 +134,7 @@ public void put(Object key, Object value) {
             }
         } else {
             // Update the existing value and keep it in the same place in the list
-            ev.value = value;
+            map.get(nv).value = value;
         }
     }
 

src/org/mozilla/javascript/JavaMembers.java

@@ -379,7 +379,9 @@ void discoverPublicMethods(Class<?> clazz, Map<MethodSignature, Method> map) {
     static void registerMethod(Map<MethodSignature, Method> map, Method method) {
         MethodSignature sig = new MethodSignature(method);
         // Array may contain methods with same signature but different return value!
-        map.putIfAbsent(sig, method);
+        if (!map.containsKey(sig)) {
+            map.put(sig, method);
+        }
     }
 
     static final class MethodSignature {