Improve diff-blob-expander icon (follow-up)

[simurai]

Follow-up to #280.

For LHC, we actually want to change the background and not the icon color, see https://github.com/github/design-infrastructure/discussions/1439#discussioncomment-1721488. So this PR:

• Reverts changing the icon color a65bb0f
• But use fg.default for the icon in DHC 7512227 because we will be using --color-diff-blob-hunk-num-bg on dotcom which is quite dark.

[changeset-bot]

🦋 Changeset detected

Latest commit: 6a0885e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/primitives	Patch

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[github-actions]

Variables changed

--- base/dist/scss/colors/_dark_high_contrast.scss	2021-12-01 08:02:35.004037363 +0000
+++ dist/scss/colors/_dark_high_contrast.scss	2021-12-01 08:02:21.628048901 +0000
@@ -16,3 +16,3 @@
     --color-diff-blob-hunk-num-bg: rgba(64,158,255,0.4);
-    --color-diff-blob-expander-icon: #0a0c10;
+    --color-diff-blob-expander-icon: #f0f3f6;
     --color-diff-blob-selected-line-highlight-mix-blend-mode: screen;
--- base/dist/scss/colors/_light_high_contrast.scss	2021-12-01 08:02:34.976037387 +0000
+++ dist/scss/colors/_light_high_contrast.scss	2021-12-01 08:02:21.596048929 +0000
@@ -16,3 +16,3 @@
     --color-diff-blob-hunk-num-bg: #9cd7ff;
-    --color-diff-blob-expander-icon: #ffffff;
+    --color-diff-blob-expander-icon: #0E1116;
     --color-diff-blob-selected-line-highlight-mix-blend-mode: multiply;

[siddharthkp]

Makes a lot of sense!