Small style fixes

Small stylistic changes that don't affect runtime.

Bug: none
Change-Id: I2e846148be13bd45bed8ae85ae53dd348da4c2d6
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7759595
Auto-Submit: Nikolay Vitkov <nvitkov@chromium.org>
Commit-Queue: Nikolay Vitkov <nvitkov@chromium.org>
Reviewed-by: Samiya Caur <samiyac@chromium.org>

Author: Lightning00Blade

front_end/panels/profiler/HeapSnapshotDataGrids.ts

@@ -300,7 +300,7 @@ export class HeapSnapshotSortableDataGrid extends Common.ObjectWrapper
       let field1 = nodeA[sortFields.fieldName1];
       // @ts-expect-error
       let field2 = nodeB[sortFields.fieldName1];
-      let result: number|(0 | 1 | -1) = field1 < field2 ? -1 : (field1 > field2 ? 1 : 0);
+      let result: number = field1 < field2 ? -1 : (field1 > field2 ? 1 : 0);
       if (!sortFields.ascending1) {
         result = -result;
       }

front_end/panels/profiler/HeapSnapshotGridNodes.ts

@@ -136,31 +136,23 @@ export class HeapSnapshotGridNode extends
     Common.ObjectWrapper.eventMixin<HeapSnapshotGridNode.EventTypes, typeof HeapSnapshotGridNodeBase>(
         HeapSnapshotGridNodeBase) {
   dataGridInternal: HeapSnapshotSortableDataGrid;
-  instanceCount: number;
-  readonly savedChildren: Map<number, HeapSnapshotGridNode>;
+  instanceCount = 0;
+  readonly savedChildren = new Map<number, HeapSnapshotGridNode>();
+  /**
+   * List of position ranges for all visible nodes: [startPos1, endPos1),...,[startPosN, endPosN)
+   * Position is an item position in the provider.
+   */
   retrievedChildrenRanges: Array<{
     from: number,
     to: number,
-  }>;
-  providerObject: HeapSnapshotModel.ChildrenProvider.ChildrenProvider|null;
-  reachableFromWindow: boolean;
+  }> = [];
+  providerObject: HeapSnapshotModel.ChildrenProvider.ChildrenProvider|null = null;
+  reachableFromWindow = false;
   populated?: boolean;
 
   constructor(tree: HeapSnapshotSortableDataGrid, hasChildren: boolean) {
     super(null, hasChildren);
     this.dataGridInternal = tree;
-    this.instanceCount = 0;
-
-    this.savedChildren = new Map();
-
-    /**
-     * List of position ranges for all visible nodes: [startPos1, endPos1),...,[startPosN, endPosN)
-     * Position is an item position in the provider.
-     */
-    this.retrievedChildrenRanges = [];
-
-    this.providerObject = null;
-    this.reachableFromWindow = false;
   }
 
   get name(): string|undefined {