fix inlay hints being offset by 1px in some cases

VS Code previously applied the `vertical-align: middle` CSS rule to all hints,
even those that have the same font style as the editor's. This results in
inlay hints being 1px lower than they should be.

This pull request adds the `isUniform` flag to `_getLayoutInfo()`'s output. It
indicates if the inlay hint styles and editor styles match. If they do, the
`vertical-align` rule is set to `baseline`, effectively disabling it.

Author: TheV360

src/vs/editor/contrib/inlayHints/browser/inlayHintsController.ts

@@ -468,7 +468,7 @@ export class InlayHintsController implements IEditorContribution {
 
 
 		//
-		const { fontSize, fontFamily, padding } = this._getLayoutInfo();
+		const { fontSize, fontFamily, padding, isUniform } = this._getLayoutInfo();
 		const fontFamilyVar = '--code-editorInlayHintsFontFamily';
 		this._editor.getContainerDomNode().style.setProperty(fontFamilyVar, fontFamily);
 
@@ -493,7 +493,7 @@ export class InlayHintsController implements IEditorContribution {
 				const cssProperties: CssProperties = {
 					fontSize: `${fontSize}px`,
 					fontFamily: `var(${fontFamilyVar}), ${EDITOR_FONT_DEFAULTS.fontFamily}`,
-					verticalAlign: 'middle',
+					verticalAlign: isUniform ? 'baseline' : 'middle',
 				};
 
 				if (isNonEmptyArray(item.hint.textEdits)) {
@@ -587,13 +587,23 @@ export class InlayHintsController implements IEditorContribution {
 
 	private _getLayoutInfo() {
 		const options = this._editor.getOption(EditorOption.inlayHints);
+		const padding = options.padding;
+
 		const editorFontSize = this._editor.getOption(EditorOption.fontSize);
+		const editorFontFamily = this._editor.getOption(EditorOption.fontFamily);
+
 		let fontSize = options.fontSize;
 		if (!fontSize || fontSize < 5 || fontSize > editorFontSize) {
 			fontSize = editorFontSize;
 		}
-		const fontFamily = options.fontFamily || this._editor.getOption(EditorOption.fontFamily);
-		return { fontSize, fontFamily, padding: options.padding };
+
+		const fontFamily = options.fontFamily || editorFontFamily;
+
+		const isUniform = !padding
+			&& fontFamily === editorFontFamily
+			&& fontSize === editorFontSize;
+
+		return { fontSize, fontFamily, padding, isUniform };
 	}
 
 	private _removeAllDecorations(): void {