edit: this PR was reverted

There were several bugs with canvas.drawLine when using DOM rendering (this codepath):

• did not correctly render with negative ui.Offsets passed as parameters
• did not respect paint.strokeCap
• did not respect paint.strokeWidth for horizontal and vertical lines

according to the api docs for canvas.drawLine, rendering of lines should be the same regardless of the paint.style.

Previously, however, failing to set paint.style to type stroke (either by omission or setting the paint.style to fill) would cause us to use DOM rendering as specified by this bool, which introduced the above mentioned bugs.

Solution for negative ui.Offsets

instead of using an svg width, height, and viewBox as the bounding box for our path, just remove all of those properties and instead set the svg overflow property to visible.

fixes: flutter/flutter#110070

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