Create more precise highlight brackets

This commit addresses too small or wrongly placed highlight brackets
especisally on windows. Because of rounding errors the bracket selection
highlight is often inconsistent. Making use of residual values plus
simplifying the logic provides better rectangle values and the highlight
is more consistent across all zooms.

Author: ShahzaibIbrahim

bundles/org.eclipse.jface.text/src/org/eclipse/jface/text/source/MatchingCharacterPainter.java

@@ -257,17 +257,15 @@ private void draw(final GC gc, final int offset) {
 		if (gc != null) {
 			gc.setForeground(fColor);
 
-			final Rectangle bounds= fTextWidget.getTextBounds(offset, offset);
+			Point offsetLocation= fTextWidget.getLocationAtOffset(offset);
 
-			// determine the character width separately, because the getTextBounds above
-			// will also include any in-line annotations (e.g. codemining annotations) in the width
 			final String matchingCharacter= fTextWidget.getText(offset, offset);
-			final int width= gc.textExtent(matchingCharacter).x;
-
-			final int height= fTextWidget.getCaret().getSize().y;
+			Point characterBounds= gc.textExtent(matchingCharacter);
+			characterBounds.y-= 1;
+			Rectangle hightlightingArea= Rectangle.of(offsetLocation, characterBounds);
 
 			// draw box around line segment
-			gc.drawRectangle(bounds.x, bounds.y + bounds.height - height, width, height - 1);
+			gc.drawRectangle(hightlightingArea);
 		} else {
 			fTextWidget.redrawRange(offset, 1, true);
 		}