 Vemurafenib and cobimetinib are FDA-approved drugs to treat advanced melanoma that has a mutated changed form of a cell protein called BRAF BRAF V600 mutation. The purpose of this study is to determine if vemurafenib and cobimetinib can be safely given to patients with this type of melanoma to shrink it before surgery. This research is being done because patients with melanoma spread to lymph node have high chance of melanoma recurrence even after lymph node removal surgery, and currently there is no approved medicine to use for patients with BRAF V600 mutant melanoma before lymph node removal surgery. 