When setting the line dash to be an empty array reset the style to Solid

An empty line dash array is indicating that it should be reset to be a
Solid line, otherwise it ends up reusing the previous settings for the
pen instead of drawing a solid line.

Fixes: QTBUG-75553
Pick-to: 6.2 6.1 5.15
Change-Id: I16466672de95da8ef0cf3fc261969e7cc6add227
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

src/quick/items/context2d/qquickcontext2dcommandbuffer.cpp

@@ -371,7 +371,10 @@ void QQuickContext2DCommandBuffer::replay(QPainter* p, QQuickContext2D::State& s
             }
             state.lineDash = pattern;
             QPen nPen = p->pen();
+            if (count > 0)
                 nPen.setDashPattern(pattern);
+            else
+                nPen.setStyle(Qt::SolidLine);
             p->setPen(nPen);
             break;
         }

tests/auto/quick/qquickcanvasitem/data/tst_line.qml

@@ -894,6 +894,37 @@ CanvasTestCase {
        comparePixel(ctx, 39,0, 0,0,0,0);
   }
 
+   function test_lineDashReset(row) {
+       var canvas = createCanvasObject(row);
+       var ctx = canvas.getContext('2d');
+       ctx.reset();
+       ctx.strokeStyle = "#ff0000";
+       ctx.lineWidth = 2;
+       var pattern = [2, 3, 5, 1, 6, 3]
+       ctx.setLineDash(pattern)
+
+       compare(ctx.getLineDash(), pattern);
+
+       pattern = []
+       ctx.setLineDash(pattern)
+       compare(ctx.getLineDash(), pattern);
+
+       ctx.beginPath();
+       ctx.moveTo(0, 0);
+       ctx.lineTo(40, 0);
+       ctx.stroke();
+
+       comparePixel(ctx, 0,0, 255,0,0,255);
+       comparePixel(ctx, 4,0, 255,0,0,255);
+       comparePixel(ctx, 5,0, 255,0,0,255);
+       comparePixel(ctx, 14,0, 255,0,0,255);
+       comparePixel(ctx, 20,0, 255,0,0,255);
+       comparePixel(ctx, 21,0, 255,0,0,255);
+       comparePixel(ctx, 22,0, 255,0,0,255);
+       comparePixel(ctx, 34,0, 255,0,0,255);
+       comparePixel(ctx, 35,0, 255,0,0,255);
+   }
+
    function test_lineDashOffset(row) {
        var canvas = createCanvasObject(row);
        var ctx = canvas.getContext('2d');