Change matMul expression to fix Windows inconsistency. (#1845)
Change matMul expression to fix Windows inconsistency. (#1845)

BUG

tensorflow/tfjs-core,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs-core,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs-core,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs-core,tensorflow/tfjs,tensorflow/tfjs-core,tensorflow/tfjs-core