Revert "Verify if crbug.com/996037 has been fixed"

This reverts commit 0a8524d2.

Reason for revert: Reverting CHECKs back to DCHECKs in the next version

Original change's description:
> Verify if crbug.com/996037 has been fixed
> 
> This patch turns a DCHECK into CHECK to verify if the DCHECK is still
> hit on production builds.
> 
> This patch will be landed into version 3903, and will be reverted in
> the next version.
> 
> Bug: 996037
> Change-Id: Ice5237e9a0761b991425b1dbe402350a6ddd9b86
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1784161
> Reviewed-by: Emil A Eklund <eae@chromium.org>
> Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#693371}

TBR=eae@chromium.org,xiaochengh@chromium.org,srinivassista@chromium.org

Change-Id: I46ca89b68b901d0d86cc03a61ea851e2bdc8fdae
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 996037
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1787031Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693885}

third_party/blink/renderer/core/animation/css_length_interpolation_type.cc

@@ -138,22 +138,23 @@ void CSSLengthInterpolationType::ApplyStandardPropertyValue(
   Length length = To<InterpolableLength>(interpolable_value)
                       .CreateLength(conversion_data, value_range_);
   if (LengthPropertyFunctions::SetLength(CssProperty(), style, length)) {
-    // TODO(crbug.com/996037): Turn this block into DCHECK in version 3904
+#if DCHECK_IS_ON()
     // Assert that setting the length on ComputedStyle directly is identical to
     // the StyleBuilder code path. This check is useful for catching differences
     // in clamping behaviour.
     Length before;
     Length after;
-    CHECK(LengthPropertyFunctions::GetLength(CssProperty(), style, before));
+    DCHECK(LengthPropertyFunctions::GetLength(CssProperty(), style, before));
     StyleBuilder::ApplyProperty(GetProperty().GetCSSProperty(), state,
                                 *CSSValue::Create(length, zoom));
-    CHECK(LengthPropertyFunctions::GetLength(CssProperty(), style, after));
-    CHECK(before.IsSpecified());
-    CHECK(after.IsSpecified());
+    DCHECK(LengthPropertyFunctions::GetLength(CssProperty(), style, after));
+    DCHECK(before.IsSpecified());
+    DCHECK(after.IsSpecified());
     const float kSlack = 0.1;
     float delta =
         FloatValueForLength(after, 100) - FloatValueForLength(before, 100);
-    CHECK_LT(std::abs(delta), kSlack);
+    DCHECK_LT(std::abs(delta), kSlack);
+#endif
     return;
   }
   StyleBuilder::ApplyProperty(GetProperty().GetCSSProperty(), state,