diff --git a/dom/html/test/browser.ini b/dom/html/test/browser.ini
index cb02f7f551b2..45b045453fab 100644
--- a/dom/html/test/browser.ini
+++ b/dom/html/test/browser.ini
@@ -26,7 +26,6 @@ skip-if = bits == 64 && (os == "mac" || os == "linux") #Bug 1646862
 [browser_containerLoadingContent.js]
 skip-if =
   os == "win" && os_version == "6.1" # Skip on Azure - frequent failure
-[browser_ImageDocument_svg_zoom.js]
 [browser_submission_flush.js]
 [browser_refresh_after_document_write.js]
 support-files =
diff --git a/dom/html/test/browser_ImageDocument_svg_zoom.js b/dom/html/test/browser_ImageDocument_svg_zoom.js
deleted file mode 100644
index c3ae6a0ff2da..000000000000
--- a/dom/html/test/browser_ImageDocument_svg_zoom.js
+++ /dev/null
@@ -1,36 +0,0 @@
-/* Any copyright is dedicated to the Public Domain.
-   http://creativecommons.org/publicdomain/zero/1.0/ */
-
-"use strict";
-
-const URL = `data:image/svg+xml,<svg viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg"><rect width="100" height="100" fill="green"/></svg>`;
-
-function test_once() {
-  return BrowserTestUtils.withNewTab(URL, async browser => {
-    return await SpecialPowers.spawn(browser, [], async function() {
-      const rect = content.document.documentElement.getBoundingClientRect();
-      info(`${rect.width}, ${rect.height}`);
-      is(
-        rect.height,
-        content.innerHeight,
-        "Should fill the viewport and not overflow"
-      );
-    });
-  });
-}
-
-add_task(async function test_with_no_text_zoom() {
-  await test_once();
-});
-
-add_task(async function test_with_text_zoom() {
-  let dpi = window.devicePixelRatio;
-
-  await SpecialPowers.pushPrefEnv({ set: [["ui.textScaleFactor", 200]] });
-  ok(
-    window.devicePixelRatio > dpi,
-    "DPI should change as a result of the pref flip"
-  );
-
-  return test_once();
-});
diff --git a/layout/svg/SVGOuterSVGFrame.cpp b/layout/svg/SVGOuterSVGFrame.cpp
index aea56c734d06..4d3e919197f8 100644
--- a/layout/svg/SVGOuterSVGFrame.cpp
+++ b/layout/svg/SVGOuterSVGFrame.cpp
@@ -40,7 +40,12 @@ NS_IMPL_FRAMEARENA_HELPERS(SVGOuterSVGFrame)
 
 SVGOuterSVGFrame::SVGOuterSVGFrame(ComputedStyle* aStyle,
                                    nsPresContext* aPresContext)
-    : SVGDisplayContainerFrame(aStyle, aPresContext, kClassID) {
+    : SVGDisplayContainerFrame(aStyle, aPresContext, kClassID),
+      mFullZoom(PresContext()->GetFullZoom()),
+      mCallingReflowSVG(false),
+      mIsRootContent(false),
+      mIsInObjectOrEmbed(false),
+      mIsInIframe(false) {
   // Outer-<svg> has CSS layout, so remove this bit:
   RemoveStateBits(NS_FRAME_SVG_LAYOUT);
   AddStateBits(NS_FRAME_REFLOW_ROOT | NS_FRAME_FONT_INFLATION_CONTAINER |
@@ -61,16 +66,6 @@ static inline ContainSizeAxes ContainSizeAxesIfApplicable(
   return aFrame->GetContainSizeAxes();
 }
 
-// This should match ImageDocument::GetZoomLevel.
-float SVGOuterSVGFrame::ComputeFullZoom() const {
-  MOZ_ASSERT(mIsRootContent);
-  MOZ_ASSERT(!mIsInIframe);
-  if (BrowsingContext* bc = PresContext()->Document()->GetBrowsingContext()) {
-    return bc->FullZoom();
-  }
-  return 1.0f;
-}
-
 void SVGOuterSVGFrame::Init(nsIContent* aContent, nsContainerFrame* aParent,
                             nsIFrame* aPrevInFlow) {
   NS_ASSERTION(aContent->IsSVGElement(nsGkAtoms::svg),
@@ -103,9 +98,6 @@ void SVGOuterSVGFrame::Init(nsIContent* aContent, nsContainerFrame* aParent,
         mIsInIframe = nsGkAtoms::iframe->Equals(*type);
       }
     }
-    if (!mIsInIframe) {
-      mFullZoom = ComputeFullZoom();
-    }
   }
 
   MaybeSendIntrinsicSizeAndRatioToEmbedder();
@@ -263,7 +255,7 @@ nsIFrame::SizeComputationResult SVGOuterSVGFrame::ComputeSize(
   LogicalSize cbSize = aCBSize;
   IntrinsicSize intrinsicSize = GetIntrinsicSize();
 
-  if (mIsRootContent) {
+  if (!mContent->GetParent()) {
     // We're the root of the outermost browsing context, so we need to scale
     // cbSize by the full-zoom so that SVGs with percentage width/height zoom:
 
@@ -272,8 +264,8 @@ nsIFrame::SizeComputationResult SVGOuterSVGFrame::ComputeSize(
                  "root should not have auto-width/height containing block");
 
     if (!mIsInIframe) {
-      cbSize.ISize(aWritingMode) *= mFullZoom;
-      cbSize.BSize(aWritingMode) *= mFullZoom;
+      cbSize.ISize(aWritingMode) *= PresContext()->GetFullZoom();
+      cbSize.BSize(aWritingMode) *= PresContext()->GetFullZoom();
     }
 
     // We also need to honour the width and height attributes' default values
@@ -282,7 +274,7 @@ nsIFrame::SizeComputationResult SVGOuterSVGFrame::ComputeSize(
     // intrinsic size.  Also note that explicit percentage values are mapped
     // into style, so the following isn't for them.)
 
-    auto* content = static_cast<SVGSVGElement*>(GetContent());
+    SVGSVGElement* content = static_cast<SVGSVGElement*>(GetContent());
 
     const SVGAnimatedLength& width =
         content->mLengthAttributes[SVGSVGElement::ATTR_WIDTH];
@@ -391,12 +383,9 @@ void SVGOuterSVGFrame::Reflow(nsPresContext* aPresContext,
     changeBits |= COORD_CONTEXT_CHANGED;
     svgElem->SetViewportSize(newViewportSize);
   }
-  if (mIsRootContent && !mIsInIframe) {
-    const auto oldZoom = mFullZoom;
-    mFullZoom = ComputeFullZoom();
-    if (oldZoom != mFullZoom) {
-      changeBits |= FULL_ZOOM_CHANGED;
-    }
+  if (mFullZoom != PresContext()->GetFullZoom() && !mIsInIframe) {
+    changeBits |= FULL_ZOOM_CHANGED;
+    mFullZoom = PresContext()->GetFullZoom();
   }
   if (changeBits && !HasAnyStateBits(NS_FRAME_FIRST_REFLOW)) {
     NotifyViewportOrTransformChanged(changeBits);
diff --git a/layout/svg/SVGOuterSVGFrame.h b/layout/svg/SVGOuterSVGFrame.h
index 68ac7caba585..8db256c690a4 100644
--- a/layout/svg/SVGOuterSVGFrame.h
+++ b/layout/svg/SVGOuterSVGFrame.h
@@ -143,18 +143,17 @@ class SVGOuterSVGFrame final : public SVGDisplayContainerFrame,
    * being used as an image.
    */
   bool IsRootOfImage();
-  float ComputeFullZoom() const;
 
   void MaybeSendIntrinsicSizeAndRatioToEmbedder();
   void MaybeSendIntrinsicSizeAndRatioToEmbedder(Maybe<IntrinsicSize>,
                                                 Maybe<AspectRatio>);
 
-  float mFullZoom = 1.0f;
+  float mFullZoom;
 
-  bool mCallingReflowSVG = false;
-  bool mIsRootContent = false;
-  bool mIsInObjectOrEmbed = false;
-  bool mIsInIframe = false;
+  bool mCallingReflowSVG;
+  bool mIsRootContent;
+  bool mIsInObjectOrEmbed;
+  bool mIsInIframe;
 };
 
 ////////////////////////////////////////////////////////////////////////