Add Isolated Memory Leak Scenarios

* boolean
* function-bridge
* map
* string

memory-tests/_measure.js

+"use strict";
+
+module.exports = function iterateAndMeasure(fn, mod = 1000000) {
+  let count = 0;
+  while (true) {
+    count++;
+    fn();
+    if (count % mod === 0) {
+      console.log(process.memoryUsage().rss / 1000000);
+    }
+  }
+}

memory-tests/boolean.js

+'use strict';
+
+var types = require('../').types;
+var iterateAndMeasure = require('./_measure');
+
+iterateAndMeasure(function() { return types.Boolean(true).getValue(); });

memory-tests/function-bridge.js

+"use strict";
+
+var sass = require("../");
+var iterateAndMeasure = require('./_measure');
+
+iterateAndMeasure(function() {
+  sass.renderSync({
+    data: '#{headings()} { color: #08c; }',
+    functions: {
+      'headings()': function() {
+        return new sass.types.String('hi');
+      }
+    }
+  });
+}, 10000);

memory-tests/map.js

+'use strict';
+
+var types = require('../').types;
+var iterateAndMeasure = require('./_measure');
+
+iterateAndMeasure(function() {
+  var key = new types.String('the-key');
+  var value = new types.String('the-value');
+
+  var map = new types.Map(1);
+
+  map.setKey(0, key);
+  map.setValue(0, value);
+
+  map.getKey(0);
+}, 100000);
+

memory-tests/string.js

+'use strict';
+
+var types = require('../').types;
+var iterateAndMeasure = require('./_measure');
+
+iterateAndMeasure(function() { return new types.String('hi'); });