sun.java2d.SunGraphics2D#dispose() method does not enough clear native memory

C Heap size is increased when sun.java2d.SunGraphics2D instances are created/removed repeatedly and HotSpot does not execute Full GC. Then OutOfMemoryError or HotSpot crash may be happened depending on Java Heap Size on Windows 32bit environment especially.

C Heap increasing is also seen on other platform, for example Linux.

Reproduced on:
- 1.7.0_151:
  Java(TM) SE Runtime Environment (build 1.7.0_151-b33)
  Java HotSpot(TM) Client VM (build 24.151-b33, mixed mode, sharing)
- 1.8.0_144:
  Java(TM) SE Runtime Environment (build 1.8.0_144-b32)
  Java HotSpot(TM) Client VM (build 25.144-b32, mixed mode, sharing)