Revert "Disabling failing blink_perf.image_decoder stories on Win."

This reverts commit 6090d226.

Reason for revert: culprit CL is being reverted in https://chromium-review.googlesource.com/c/chromium/src/+/1178841

Original change's description:
> Disabling failing blink_perf.image_decoder stories on Win.
> 
> Bug: 874810
> Change-Id: I11ff44a55b4f2b14b8ba0a4ab5bb4e0f54cd8ef8
> TBR: nednguyen@google.com
> NOTRY: true
> Reviewed-on: https://chromium-review.googlesource.com/1177882
> Reviewed-by: Annie Sullivan <sullivan@chromium.org>
> Commit-Queue: Annie Sullivan <sullivan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#583658}

TBR=sullivan@chromium.org

Change-Id: Ia80a8b6809d909fff687bd12cace06fe447eb141
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 874810
Reviewed-on: https://chromium-review.googlesource.com/1178861Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#583798}

tools/perf/expectations.config

@@ -18,10 +18,6 @@ crbug.com/853738 [ Android_Webview ] blink_perf.canvas/draw-video-to-hw-accelera
 crbug.com/853738 [ Android_Webview ] blink_perf.canvas/upload-video-to-sub-texture.html [ Skip ]
 crbug.com/853738 [ Android_Webview ] blink_perf.canvas/upload-video-to-texture.html [ Skip ]
 
-# Benchmark: blink_perf.image_decoder
-crbug.com/874810 [ Win ] blink_perf.image_decoder/decode-lossy-webp.html [ Skip ]
-crbug.com/874810 [ Win ] blink_perf.image_decoder/decode-png-palette-opaque.html [ Skip ]
-
 # Benchmark: blink_perf.layout
 crbug.com/551950 [ Android_Svelte ] blink_perf.layout/* [ Skip ]
 crbug.com/832686 [ Nexus_5 ] blink_perf.layout/subtree-detaching.html [ Skip ]