fix(client): add ES5 shim
fix(client): add ES5 shim

Karma client now uses core-js ES5 shim in order to support IE8.
Usage of dom-serializer had previously broken IE8 support.

Closes #1529

stevemao/karma,simudream/karma,aiboy/karma,powerkid/karma,chrisirhc/karma,Sanjo/karma,mprobst/karma,david-garcia-nete/karma,tomkuk/karma,pedrotcaraujo/karma,kahwee/karma,patrickporto/karma,chrisirhc/karma,kahwee/karma,jjoos/karma,ernsheong/karma,Sanjo/karma,IsaacChapman/karma,buley/karma,wesleycho/karma,karma-runner/karma,jamestalmage/karma,SamuelMarks/karma,marthinus-engelbrecht/karma,johnjbarton/karma,marthinus-engelbrecht/karma,timebackzhou/karma,tomkuk/karma,harme199497/karma,powerkid/karma,shirish87/karma,maksimr/karma,Dignifiedquire/karma,pmq20/karma,jjoos/karma,oyiptong/karma,IveWong/karma,ernsheong/karma,Dignifiedquire/karma,oyiptong/karma,astorije/karma,kahwee/karma,johnjbarton/karma,Sanjo/karma,johnjbarton/karma,maksimr/karma,patrickporto/karma,panrafal/karma,astorije/karma,marthinus-engelbrecht/karma,skycocker/karma,xiaoking/karma,pedrotcaraujo/karma,pmq20/karma,IsaacChapman/karma,karma-runner/karma,wesleycho/karma,marthinus-engelbrecht/karma,codedogfish/karma,tomkuk/karma,mprobst/karma,clbond/karma,buley/karma,karma-runner/karma,unional/karma,panrafal/karma,shirish87/karma,IveWong/karma,timebackzhou/karma,buley/karma,stevemao/karma,skycocker/karma,chrisirhc/karma,karma-runner/karma,clbond/karma,pedrotcaraujo/karma,powerkid/karma,unional/karma,unional/karma,IsaacChapman/karma,skycocker/karma,simudream/karma,david-garcia-nete/karma,tomkuk/karma,clbond/karma,pmq20/karma,oyiptong/karma,simudream/karma,panrafal/karma,timebackzhou/karma,xiaoking/karma,Dignifiedquire/karma,aiboy/karma,kahwee/karma,Dignifiedquire/karma,maksimr/karma,unional/karma,stevemao/karma,harme199497/karma,jjoos/karma,jjoos/karma,aiboy/karma,chrisirhc/karma,powerkid/karma,johnjbarton/karma,patrickporto/karma,shirish87/karma,buley/karma,IsaacChapman/karma,astorije/karma,harme199497/karma,pedrotcaraujo/karma,SamuelMarks/karma,skycocker/karma,IveWong/karma,aiboy/karma,jamestalmage/karma,codedogfish/karma,david-garcia-nete/karma,SamuelMarks/karma,clbond/karma,mprobst/karma,oyiptong/karma,patrickporto/karma,pmq20/karma,wesleycho/karma,Sanjo/karma,harme199497/karma,IveWong/karma,wesleycho/karma,astorije/karma,xiaoking/karma,timebackzhou/karma,codedogfish/karma,simudream/karma,stevemao/karma,jamestalmage/karma,xiaoking/karma,ernsheong/karma,jamestalmage/karma,codedogfish/karma