Clean up minified and non-minified sources for wtb #751

Job	Run time
Test Browser on macOS (safari, disabled)	1m 36s
Test Build	2m 10s
Test Browser on macOS (safari, main)	1m 2s
Test Browser on Linux (chrome, disabled)	1m 6s
Test Browser on macOS (safari, default)	2m 9s
Test Browser on Linux (firefox, disabled)	1m 17s
Test Browser on Linux (firefox, main)	48s
Test Browser on Linux (chrome, main)	39s
Test Shell (spidermonkey, disabled)	2m 15s
Test Shell (v8, main)	46s
Test Shell (jsc, main)	46s
Test Browser on Linux (firefox, default)	1m 29s
Test Browser on Linux (chrome, default)	1m 13s
Test Shell (v8, disabled)	1m 47s
Test Shell (spidermonkey, main)	49s
Test Shell (jsc, disabled)	1m 46s
Test Shell (jsc, default)	2m 1s
Test Shell (spidermonkey, default)	5m 6s
Test Shell (v8, default)	2m 38s
	31m 23s

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