The ornamental design for a electric bathbrush, as shown and described.
FIG. 1 is a first perspective view of an electric bath brush showing my new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top plan view thereof;
FIG. 8 is a bottom plan view thereof; and,
FIG. 9 is an enlarged view of part 9 in FIG. 1.
The broken lines in the drawings depict portions of the electric bath brush that form no part of the claimed design. The dot-dash broken lines shown in FIGS. 1 and 9 are to show enlarged views and form no part of the claimed design.