The ornamental design for a gasburner, as shown and described.
1. Gas burner
1.1: Perspective
1.2: Perspective
1.3: Perspective
1.4: Front
1.5: Back
1.6: Right
1.7: Left
1.8: Top
1.9: Bottom
1.10: Enlarged view of the area slightly above the center in figure 1.3
1.11: Perspective view of the gas burner of figure 1.1 in a position of use.
This article is a gas burner used for cooking; the broken lines in the figures depict portions of the gas burner that form no part of the claimed design. The additional broken lines in figure 1.11 depict environmental subject matter that forms no part of the claimed design.