Adding support for CSP-compliant js sources.
Adding support for CSP-compliant js sources.

sethladd/dart_to_js_script_rewriter,kasperpeulen/dart_to_js_script_rewriter,kevmoo/dart_to_js_script_rewriter,Workiva/dart_to_js_script_rewriter,d2m/dart_to_js_script_rewriter,kasperpeulen/dart_to_js_script_rewriter,Workiva/dart_to_js_script_rewriter,FaisalAbid/dart_to_js_script_rewriter,FaisalAbid/dart_to_js_script_rewriter,sethladd/dart_to_js_script_rewriter,maxwellpeterson-wf/dart_to_js_script_rewriter,d2m/dart_to_js_script_rewriter,domesticmouse/dart_to_js_script_rewriter,maxwellpeterson-wf/dart_to_js_script_rewriter,kevmoo/dart_to_js_script_rewriter,domesticmouse/dart_to_js_script_rewriter