Simplify fast buffer constructor

lib/buffer.js

@@ -114,7 +114,7 @@ function Buffer (subject, encoding, offset) {
 
     if (this.length > Buffer.poolSize) {
       // Big buffer, just alloc one.
-      this.parent = new SlowBuffer(subject, encoding);
+      this.parent = new SlowBuffer(this.length);
       this.offset = 0;
 
     } else {
@@ -123,21 +123,18 @@ function Buffer (subject, encoding, offset) {
       this.parent = pool;
       this.offset = pool.used;
       pool.used += this.length;
+    }
 
-      // Do we need to write stuff?
-      if (type !== 'number') {
     // Assume object is an array
-        if (type === 'object') {
+    if (Array.isArray(subject)) {
       for (var i = 0; i < this.length; i++) {
         this.parent[i + this.offset] = subject[i];
       }
-        } else {
+    } else if (type == 'string') {
       // We are a string
       this.write(subject, 0, encoding);
     }
   }
-    }
-  }
 
   SlowBuffer.makeFastBuffer(this.parent, this, this.offset, this.length);
 }