Fixed leak of render target associated with ColorBuffer.
Fixed leak of render target associated with ColorBuffer.

Following r853, I am assuming that any render target returned by FrameBuffer::getRenderTarget has to be released. Updating the usage of getRenderTarget to reflect that.

This is not reproducible in Chrome at the moment but it will be once I start rendering to pbuffers.

I ran the WebGL conformance tests. No regressions or crashes.
Review URL: http://codereview.appspot.com/5451110

git-svn-id: a070b70d2b8c44c266a3870c0cddd9a0ee470458@903 736b8ea6-26fd-11df-bfd4-992fa37f6226

jgcaaprom/android_external_chromium_org_third_party_angle,KTXSoftware/angleproject,mybios/angle,xuxiandi/angleproject,cvsuser-chromium/chromium-third-party_angle_dx11,cvsuser-chromium/chromium-third-party_angle_dx11,xuxiandi/angleproject,vvuk/angle-old,android-ia/platform_external_chromium_org_third_party_angle,ehsan/angle,MSOpenTech/angle,mlfarrell/angle,larsbergstrom/angle,ecoal95/angle,ehsan/angle,nandhanurrevanth/angle,ghostoy/angle,MIPS/external-chromium_org-third_party-angle_dx11,jgcaaprom/android_external_chromium_org_third_party_angle,domokit/waterfall,xin3liang/platform_external_chromium_org_third_party_angle,ehsan/angle,vvuk/angle,KTXSoftware/angleproject,android-ia/platform_external_chromium_org_third_party_angle,ecoal95/angle,shairai/angleproject,csa7mdm/angle,MIPS/external-chromium_org-third_party-angle_dx11,android-ia/platform_external_chromium_org_third_party_angle_dx11,crezefire/angle,ppy/angle,android-ia/platform_external_chromium_org_third_party_angle,larsbergstrom/angle,vvuk/angle,geekboxzone/lollipop_external_chromium_org_third_party_angle,mrobinson/rust-angle,xin3liang/platform_external_chromium_org_third_party_angle_dx11,csa7mdm/angle,shairai/angleproject,MIPS/external-chromium_org-third_party-angle,ghostoy/angle,cantren/angleproject,mybios/angle,KTXSoftware/angleproject,themusicgod1/angleproject,nandhanurrevanth/angle,stammen/angleproject,mikolalysenko/angle,ghostoy/angle,jgcaaprom/android_external_chromium_org_third_party_angle,ecoal95/angle,bsergean/angle,pombreda/angleproject,shairai/angleproject,mlfarrell/angle,cantren/angleproject,RepublicMaster/angleproject,MSOpenTech/angle-win8.0,cvsuser-chromium/chromium-third-party_angle_dx11,themusicgod1/angleproject,themusicgod1/angleproject,cantren/angleproject,mrobinson/rust-angle,vvuk/angle-old,ppy/angle,ecoal95/angle,stammen/angleproject,xin3liang/platform_external_chromium_org_third_party_angle,ghostoy/angle,android-ia/platform_external_chromium_org_third_party_angle_dx11,geekboxzone/lollipop_external_chromium_org_third_party_angle,vvuk/angle-old,bsergean/angle,cvsuser-chromium/chromium-third-party_angle_dx11,MSOpenTech/angle,MIPS/external-chromium_org-third_party-angle,KalebDark/angleproject,larsbergstrom/angle,nandhanurrevanth/angle,larsbergstrom/angle,mikolalysenko/angle,crezefire/angle,xin3liang/platform_external_chromium_org_third_party_angle,pombreda/angleproject,MSOpenTech/angle-win8.0,geekboxzone/lollipop_external_chromium_org_third_party_angle,vvuk/angle,vvuk/angle,mikolalysenko/angle,ehsan/angle,RepublicMaster/angleproject,MIPS/external-chromium_org-third_party-angle,mlfarrell/angle,geekboxzone/lollipop_external_chromium_org_third_party_angle,xuxiandi/angleproject,mrobinson/rust-angle,mikolalysenko/angle,mrobinson/rust-angle,xin3liang/platform_external_chromium_org_third_party_angle_dx11,csa7mdm/angle,crezefire/angle,KalebDark/angleproject,pombreda/angleproject,nandhanurrevanth/angle,mybios/angle,MSOpenTech/angle,jgcaaprom/android_external_chromium_org_third_party_angle,xin3liang/platform_external_chromium_org_third_party_angle_dx11,bsergean/angle,stammen/angleproject,domokit/waterfall,RepublicMaster/angleproject,KalebDark/angleproject,xin3liang/platform_external_chromium_org_third_party_angle,android-ia/platform_external_chromium_org_third_party_angle_dx11,xuxiandi/angleproject,MSOpenTech/angle,mybios/angle,shairai/angleproject,cantren/angleproject,MIPS/external-chromium_org-third_party-angle,MSOpenTech/angle-win8.0,KTXSoftware/angleproject,KalebDark/angleproject,RepublicMaster/angleproject,bsergean/angle,KTXSoftware/angleproject,ppy/angle,crezefire/angle,pombreda/angleproject,MSOpenTech/angle-win8.0,ppy/angle,android-ia/platform_external_chromium_org_third_party_angle_dx11,ecoal95/angle,MIPS/external-chromium_org-third_party-angle_dx11,stammen/angleproject,themusicgod1/angleproject,vvuk/angle-old,xin3liang/platform_external_chromium_org_third_party_angle_dx11,MIPS/external-chromium_org-third_party-angle_dx11,csa7mdm/angle,mlfarrell/angle,android-ia/platform_external_chromium_org_third_party_angle,mrobinson/rust-angle