Large increase in RAM usage with Qt 5.2

Complex QML applications can exhibit much larger RAM usage (over 100MB increase) with Qt 5.2. This appears to be primarily due to allocations from v4.

As an example, each binding now allocates at least a 128 byte FunctionObject and a 80 byte prototype Object.

With Qt 5.3, the base size of Object has also increased (from 72 to 84).