Week 35

Demos
  * Nbody: enable device switch using radio buttons
  * PathIntegrals: disable CL<->GL interop when CPU is used

Layout Tests
  * Changed data structure in Image Test
  * Make a rebaseline in webcl-test-arg-types-const-expected.txt
  * Make a progression in webcl-test-instanceof.html

Build
  * Makes it possible to build WebCL without WebGL support