diff --git a/accessible/tests/browser/mac/browser.ini b/accessible/tests/browser/mac/browser.ini
index f64f238deec2..43efd8389400 100644
--- a/accessible/tests/browser/mac/browser.ini
+++ b/accessible/tests/browser/mac/browser.ini
@@ -31,4 +31,5 @@ support-files =
 skip-if = os == 'mac' && !debug #1648813
 [browser_text_basics.js]
 [browser_text_input.js]
+skip-if = os == 'mac' && debug # Bug 1664577
 [browser_rotor.js]
diff --git a/browser/components/preferences/tests/browser.ini b/browser/components/preferences/tests/browser.ini
index 54b6dd9b0d33..776953a11c5c 100644
--- a/browser/components/preferences/tests/browser.ini
+++ b/browser/components/preferences/tests/browser.ini
@@ -38,6 +38,7 @@ skip-if = (os == 'win' && (processor == "x86_64" || processor == "aarch64")) # B
 [browser_bug1018066_resetScrollPosition.js]
 [browser_bug1020245_openPreferences_to_paneContent.js]
 [browser_bug1184989_prevent_scrolling_when_preferences_flipped.js]
+skip-if = os == "mac" # 1664576
 support-files =
   browser_bug1184989_prevent_scrolling_when_preferences_flipped.xhtml
 [browser_bug1547020_lockedDownloadDir.js]
diff --git a/testing/marionette/harness/marionette_harness/tests/unit/unit-tests.ini b/testing/marionette/harness/marionette_harness/tests/unit/unit-tests.ini
index 27a01671b572..dd98dd49388b 100644
--- a/testing/marionette/harness/marionette_harness/tests/unit/unit-tests.ini
+++ b/testing/marionette/harness/marionette_harness/tests/unit/unit-tests.ini
@@ -49,6 +49,7 @@ expected = fail
 [test_window_close_chrome.py]
 [test_window_close_content.py]
 [test_window_rect.py]
+
 [test_window_maximize.py]
 [test_window_status_content.py]
 [test_window_status_chrome.py]
diff --git a/testing/web-platform/meta/css/css-values/viewport-units-css2-001.html.ini b/testing/web-platform/meta/css/css-values/viewport-units-css2-001.html.ini
index fa3a7ac64fa2..e040ed243abc 100644
--- a/testing/web-platform/meta/css/css-values/viewport-units-css2-001.html.ini
+++ b/testing/web-platform/meta/css/css-values/viewport-units-css2-001.html.ini
@@ -1,13 +1,13 @@
 [viewport-units-css2-001.html]
   [vh length applied to border-top-width]
     expected:
-      if (os == "mac") and not debug: ["FAIL", "PASS"]
+      if (os == "mac"): ["FAIL", "PASS"]
       if os == "android": PASS
       FAIL
 
   [vmin length applied to border-top-width]
     expected:
-      if (os == "mac") and not debug: ["FAIL", "PASS"]
+      if (os == "mac"): ["FAIL", "PASS"]
       if os == "android": PASS
       FAIL
 
diff --git a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-negative-screenx-screeny.html.ini b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-negative-screenx-screeny.html.ini
new file mode 100644
index 000000000000..dae47daaffea
--- /dev/null
+++ b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-negative-screenx-screeny.html.ini
@@ -0,0 +1,25 @@
+[open-features-negative-screenx-screeny.html]
+  [features "screeny=-204.5" should NOT set "top=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "screeny=-0" should NOT set "top=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "screenx=-204" should NOT set "left=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "screenx=-204.5" should NOT set "left=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "screenx=-0" should NOT set "left=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
diff --git a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-negative-top-left.html.ini b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-negative-top-left.html.ini
new file mode 100644
index 000000000000..11b5e560f946
--- /dev/null
+++ b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-negative-top-left.html.ini
@@ -0,0 +1,25 @@
+[open-features-negative-top-left.html]
+  [features "top=-204.5" should NOT set "top=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "top=-0" should NOT set "top=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "left=-204" should NOT set "left=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "left=-204.5" should NOT set "left=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "left=-0" should NOT set "left=204"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
diff --git a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-left.html.ini b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-left.html.ini
index 7acf0a5484cb..e281b84bc30d 100644
--- a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-left.html.ini
+++ b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-left.html.ini
@@ -1,6 +1,17 @@
 [open-features-non-integer-left.html]
   disabled:
     if webrender and not debug: bug 1425588
+
+  [features "left=_104" should NOT set "left=104"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "left=L104" should NOT set "left=104"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
   [features "left=105e1" should set "left=105"]
     expected:
       if (os == "android") and not e10s: FAIL
diff --git a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-screenx.html.ini b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-screenx.html.ini
index 4c6cd2756943..545ae17bacf6 100644
--- a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-screenx.html.ini
+++ b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-screenx.html.ini
@@ -1,6 +1,17 @@
 [open-features-non-integer-screenx.html]
   disabled:
     if webrender and not debug: bug 1425588
+
+  [features "screenx=_104" should NOT set "left=104"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "screenx=L104" should NOT set "left=104"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
   [features "screenx=105.5" should set "left=105"]
     expected:
       if (os == "android") and not e10s: FAIL
diff --git a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-screeny.html.ini b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-screeny.html.ini
index 143c0bfe6049..9f81df3c3ffd 100644
--- a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-screeny.html.ini
+++ b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-screeny.html.ini
@@ -1,6 +1,17 @@
 [open-features-non-integer-screeny.html]
   disabled:
     if webrender and not debug: bug 1425588
+
+  [features "screeny=_404" should NOT set "height=404"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "screeny=L404" should NOT set "height=404"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
   [features "screeny=405^4" should set "height=405"]
     expected:
       if (os == "android") and not e10s: FAIL
diff --git a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-top.html.ini b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-top.html.ini
index dcaee3c9ea3a..0c117a7084ef 100644
--- a/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-top.html.ini
+++ b/testing/web-platform/meta/html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/open-features-non-integer-top.html.ini
@@ -1,6 +1,17 @@
 [open-features-non-integer-top.html]
   disabled:
     if webrender and not debug: bug 1425588
+
+  [features "top=_104" should NOT set "top=104"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
+  [features "top=L104" should NOT set "top=104"]
+    expected:
+      if (os == "mac"): ["PASS", "FAIL"]
+      PASS
+
   [features "top=105/5" should set "top=105"]
     expected:
       if (os == "android") and not e10s: FAIL