Support early and late command evaluation with <! >! <!@ and >!@. Review URL: http://codereview.chromium.org/42375
Support early and late command evaluation with <! >! <!@ and >!@.
Review URL: http://codereview.chromium.org/42375

git-svn-id: e7e1075985beda50ea81ac4472467b4f6e91fc78@373 78cadc50-ecff-11dd-a971-7dbc132099af

AWhetter/gyp,trafi/gyp,sloanyang/gyp,amoikevin/gyp,bnoordhuis/gyp,adblockplus/gyp,mistydemeo/gyp,pyokagan/gyp,openpeer/webrtc-gyp,sfiera/gyp,AWhetter/gyp,okwasi/gyp,lianliuwei/gyp,okumura/gyp,ttyangf/pdfium_gyp,bnoordhuis/gyp,ttyangf/gyp,dougbeal/gyp,sdklite/gyp,luvit/gyp,openpeer/webrtc-gyp,tarc/gyp,yangrongwei/gyp,bnq4ever/gypgoogle,sanyaade-teachings/gyp,trafi/gyp,pyokagan/gyp,android-ia/platform_external_chromium_org_tools_gyp,springmeyer/gyp,erikge/watch_gyp,erikge/watch_gyp,sanyaade-teachings/gyp,svn2github/gyp,turbulenz/gyp,Chilledheart/gyp,luvit/gyp,clar/gyp,mgamer/gyp,MIPS/external-chromium_org-tools-gyp,mumble-voip/libmumble-gyp,enkripsi/gyp,azunite/gyp,clar/gyp,xin3liang/platform_external_chromium_org_tools_gyp,cchamberlain/gyp,channing/gyp,yinquan529/platform-external-chromium_org-tools-gyp,openpeer/webrtc-gyp,mkrautz/gyp-libmumble,okumura/gyp,Omegaphora/external_chromium_org_tools_gyp,Danath/gyp,erikge/watch_gyp,xin3liang/platform_external_chromium_org_tools_gyp,bulldy80/gyp_unofficial,azunite/gyp_20150930,sanyaade-teachings/gyp,amoikevin/gyp,omasanori/gyp,mgamer/gyp,Omegaphora/external_chromium_org_tools_gyp,channing/gyp,Danath/gyp,amoikevin/gyp,sdklite/gyp,cysp/gyp,Jack-Q/GYP-copy,msc-/gyp,saghul/gyn,bdarnell/gyp,bpsinc-native/src_tools_gyp,omasanori/gyp,Jack-Q/GYP-copy,erikge/watch_gyp,pyokagan/gyp,azunite/gyp_20150930,AWhetter/gyp,bnq4ever/gypgoogle,azunite/gyp,kevinchen3315/gyp-git,bdarnell/gyp,saghul/gyn,LazyCodingCat/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,android-ia/platform_external_chromium_org_tools_gyp,pandaxcl/gyp,bulldy80/gyp_unofficial,AOSPU/external_chromium_org_tools_gyp,enkripsi/gyp,lukeweber/gyp-override,pandaxcl/gyp,Chilledheart/gyp,cysp/gyp,msc-/gyp,azunite/gyp_20150930,saghul/gyn,mumble-voip/libmumble-gyp,mgamer/gyp,android-ia/platform_external_chromium_org_tools_gyp,Chilledheart/gyp,mapbox/gyp,kevinchen3315/gyp-git,LazyCodingCat/gyp,pyokagan/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,duanhjlt/gyp,LazyCodingCat/gyp,clar/gyp,lukeweber/gyp-override,kevinchen3315/gyp-git,ttyangf/pdfium_gyp,chromium/gyp,sanyaade-teachings/gyp,cysp/gyp,ttyangf/pdfium_gyp,msc-/gyp,brson/gyp,springmeyer/gyp,LazyCodingCat/gyp,omasanori/gyp,alexcrichton/gyp,AOSPU/external_chromium_org_tools_gyp,brson/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,lianliuwei/gyp,lianliuwei/gyp,yinquan529/platform-external-chromium_org-tools-gyp,mistydemeo/gyp,ttyangf/pdfium_gyp,yinquan529/platform-external-chromium_org-tools-gyp,MIPS/external-chromium_org-tools-gyp,AOSPU/external_chromium_org_tools_gyp,sport-monkey/GYP,mkrautz/gyp-libmumble,yjhjstz/gyp,azunite/gyp,ryfx/gyp,ttyangf/gyp,bnoordhuis/gyp,svn2github/kgyp,ryfx/gyp,enkripsi/gyp,svn2github/gyp,yangrongwei/gyp,svn2github/gyp,MIPS/external-chromium_org-tools-gyp,bnoordhuis/gyp,duanhjlt/gyp,cchamberlain/gyp,turbulenz/gyp,azunite/gyp_20150930,turbulenz/gyp,tarc/gyp,omasanori/gyp,tarc/gyp,IllusionRom-deprecated/android_platform_external_chromium_org_tools_gyp,sloanyang/gyp,amoikevin/gyp,ttyangf/gyp,Danath/gyp,pyokagan/gyp,luvit/gyp,bnq4ever/gypgoogle,sport-monkey/GYP,mkrautz/gyp-libmumble,carlTLR/gyp,sdklite/gyp,mapbox/gyp,adblockplus/gyp,tarc/gyp,lukeweber/gyp-override,bulldy80/gyp_unofficial,enkripsi/gyp,bnq4ever/gypgoogle,sloanyang/gyp,dougbeal/gyp,azunite/gyp_20150930,bpsinc-native/src_tools_gyp,dougbeal/gyp,Jack-Q/GYP-copy,chromium/gyp,Jack-Q/GYP-copy,chromium/gyp,ttyangf/pdfium_gyp,carlTLR/gyp,adblockplus/gyp,chromium/gyp,sdklite/gyp,brson/gyp,springmeyer/gyp,msc-/gyp,turbulenz/gyp,kevinchen3315/gyp-git,mapbox/gyp,svn2github/gyp,cchamberlain/gyp,msc-/gyp,mumble-voip/libmumble-gyp,alexcrichton/gyp,bulldy80/gyp_unofficial,saghul/gyn,channing/gyp,sfiera/gyp,cchamberlain/gyp,yangrongwei/gyp,ttyangf/gyp,erikge/watch_gyp,okwasi/gyp,pandaxcl/gyp,luvit/gyp,saghul/gyn,mgamer/gyp,trafi/gyp,trafi/gyp,LazyCodingCat/gyp,AWhetter/gyp,bnoordhuis/gyp,svn2github/kgyp,ttyangf/gyp,azunite/gyp,AOSPU/external_chromium_org_tools_gyp,Phuehvk/gyp,Omegaphora/external_chromium_org_tools_gyp,cchamberlain/gyp,duanhjlt/gyp,Phuehvk/gyp,Jack-Q/GYP-copy,AWhetter/gyp,channing/gyp,amoikevin/gyp,ryfx/gyp,yinquan529/platform-external-chromium_org-tools-gyp,adblockplus/gyp,carlTLR/gyp,svn2github/gyp,sport-monkey/GYP,yjhjstz/gyp,android-ia/platform_external_chromium_org_tools_gyp,mapbox/gyp,okumura/gyp,chromium/gyp,mgamer/gyp,lukeweber/gyp-override,azunite/gyp,Omegaphora/external_chromium_org_tools_gyp,clar/gyp,svn2github/kgyp,MIPS/external-chromium_org-tools-gyp,mapbox/gyp,bdarnell/gyp,brson/gyp,bpsinc-native/src_tools_gyp,Phuehvk/gyp,lianliuwei/gyp,okwasi/gyp,duanhjlt/gyp,okumura/gyp,springmeyer/gyp,springmeyer/gyp,mumble-voip/libmumble-gyp,dougbeal/gyp,carlTLR/gyp,Danath/gyp,bdarnell/gyp,openpeer/webrtc-gyp,sloanyang/gyp,Chilledheart/gyp,IllusionRom-deprecated/android_platform_external_chromium_org_tools_gyp,Phuehvk/gyp,ryfx/gyp,alexcrichton/gyp,pandaxcl/gyp,bnq4ever/gypgoogle,yjhjstz/gyp,okwasi/gyp,turbulenz/gyp,mistydemeo/gyp,yangrongwei/gyp,xin3liang/platform_external_chromium_org_tools_gyp,sanyaade-teachings/gyp,duanhjlt/gyp,ryfx/gyp,dougbeal/gyp,trafi/gyp,Danath/gyp,sport-monkey/GYP,bpsinc-native/src_tools_gyp,carlTLR/gyp,clar/gyp,xin3liang/platform_external_chromium_org_tools_gyp,pandaxcl/gyp,yjhjstz/gyp,sport-monkey/GYP,adblockplus/gyp,IllusionRom-deprecated/android_platform_external_chromium_org_tools_gyp,sdklite/gyp,svn2github/kgyp,cysp/gyp,bulldy80/gyp_unofficial,alexcrichton/gyp,yjhjstz/gyp,enkripsi/gyp,mkrautz/gyp-libmumble,IllusionRom-deprecated/android_platform_external_chromium_org_tools_gyp,sfiera/gyp,tarc/gyp,openpeer/webrtc-gyp,Phuehvk/gyp,mistydemeo/gyp,geekboxzone/lollipop_external_chromium_org_tools_gyp,cysp/gyp,svn2github/kgyp,Chilledheart/gyp