diff --git a/encoding/encodeInto.any.js b/encoding/encodeInto.any.js
index 7e18c812499a52..807c753980377b 100644
--- a/encoding/encodeInto.any.js
+++ b/encoding/encodeInto.any.js
@@ -1,3 +1,21 @@
+function createBuffer(type, length = 0) {
+  if (type === "ArrayBuffer") {
+    return new ArrayBuffer(length);
+  } else {
+    // See https://github.com/whatwg/html/issues/5380 for why not `new SharedArrayBuffer()`
+    // WebAssembly.Memory's size is in multiples of 64 KiB
+    return new WebAssembly.Memory({ shared:true, initial:1, maximum:1 }).buffer;
+  }
+}
+
+function createViewWithBuffer(type, length) {
+  if (type === "ArrayBuffer") {
+    return new Uint8Array(new ArrayBuffer(length));
+  } else {
+    return new Uint8Array(createBuffer(type), 0, length);
+  }
+}
+
 [
   {
     "input": "Hi",
@@ -77,15 +95,15 @@
     ["ArrayBuffer", "SharedArrayBuffer"].forEach(arrayBufferOrSharedArrayBuffer => {
       test(() => {
         // Setup
-        const bufferLength = testData.destinationLength + destinationData.bufferIncrease,
-              destinationOffset = destinationData.destinationOffset,
-              destinationLength = testData.destinationLength,
-              destinationFiller = destinationData.filler,
-              encoder = new TextEncoder(),
-              buffer = new self[arrayBufferOrSharedArrayBuffer](bufferLength),
-              view = new Uint8Array(buffer, destinationOffset, destinationLength),
-              fullView = new Uint8Array(buffer),
-              control = new Array(bufferLength);
+        const bufferLength = testData.destinationLength + destinationData.bufferIncrease;
+        const destinationOffset = destinationData.destinationOffset;
+        const destinationLength = testData.destinationLength;
+        const destinationFiller = destinationData.filler;
+        const encoder = new TextEncoder();
+        const buffer = createBuffer(arrayBufferOrSharedArrayBuffer, bufferLength);
+        const view = new Uint8Array(buffer, destinationOffset, destinationLength);
+        const fullView = new Uint8Array(buffer);
+        const control = new Array(bufferLength);
         let byte = destinationFiller;
         for (let i = 0; i < bufferLength; i++) {
           if (destinationFiller === "random") {
@@ -105,6 +123,8 @@
         // Remainder
         assert_equals(result.read, testData.read);
         assert_equals(result.written, testData.written.length);
+        // This will not check the entire buffer allocated by WebAssembly.Memory, but we'll trust
+        // that this is sufficient.
         for (let i = 0; i < bufferLength; i++) {
           if (i < destinationOffset || i >= (destinationOffset + testData.written.length)) {
             assert_equals(fullView[i], control[i]);
@@ -128,19 +148,17 @@
  Float64Array].forEach(view => {
   ["ArrayBuffer", "SharedArrayBuffer"].forEach((arrayBufferOrSharedArrayBuffer) => {
     test(() => {
-      assert_throws_js(TypeError, () => new TextEncoder().encodeInto("", new view(new self[arrayBufferOrSharedArrayBuffer](0))));
+      assert_throws_js(TypeError, () => new TextEncoder().encodeInto("", createViewWithBuffer(arrayBufferOrSharedArrayBuffer, 0)));
     }, "Invalid encodeInto() destination: " + view.name + ", backed by: " + arrayBufferOrSharedArrayBuffer);
   });
 });
 
 ["ArrayBuffer", "SharedArrayBuffer"].forEach((arrayBufferOrSharedArrayBuffer) => {
   test(() => {
-    assert_throws_js(TypeError, () => new TextEncoder().encodeInto("", new self[arrayBufferOrSharedArrayBuffer](10)));
+    assert_throws_js(TypeError, () => new TextEncoder().encodeInto("", createBuffer(arrayBufferOrSharedArrayBuffer, 10)));
   }, "Invalid encodeInto() destination: " + arrayBufferOrSharedArrayBuffer);
 });
 
-
-
 test(() => {
   const buffer = new ArrayBuffer(10),
         view = new Uint8Array(buffer);
diff --git a/encoding/streams/decode-utf8.any.js b/encoding/streams/decode-utf8.any.js
index 421b98c2eea537..27e14e47ab59b7 100644
--- a/encoding/streams/decode-utf8.any.js
+++ b/encoding/streams/decode-utf8.any.js
@@ -5,11 +5,22 @@
 'use strict';
 
 ["ArrayBuffer", "SharedArrayBuffer"].forEach((arrayBufferOrSharedArrayBuffer) => {
-  const inputChunkData = [73, 32, 240, 159, 146, 153, 32, 115, 116,
-                          114, 101, 97, 109, 115]
+  const inputChunkData = [73, 32, 240, 159, 146, 153, 32, 115, 116, 114, 101, 97, 109, 115];
 
-  const emptyChunk = new Uint8Array(new self[arrayBufferOrSharedArrayBuffer](0));
-  const inputChunk = new Uint8Array(new self[arrayBufferOrSharedArrayBuffer](inputChunkData.length));
+  function createViewWithBuffer(type, length) {
+    if (type === "ArrayBuffer") {
+      return new Uint8Array(new ArrayBuffer(length));
+    } else {
+      // See https://github.com/whatwg/html/issues/5380 for why not `new SharedArrayBuffer()`
+      // WebAssembly.Memory's size is in multiples of 64 KiB
+      const size = (length === 0) ? 0 : 1;
+      const buffer = new WebAssembly.Memory({ shared:true, initial:size, maximum:size }).buffer;
+      return new Uint8Array(buffer, 0, length);
+    }
+  }
+
+  const emptyChunk = createViewWithBuffer(arrayBufferOrSharedArrayBuffer, 0);
+  const inputChunk = createViewWithBuffer(arrayBufferOrSharedArrayBuffer, inputChunkData.length);
 
   inputChunk.set(inputChunkData);
 
diff --git a/encoding/textdecoder-copy.any.js b/encoding/textdecoder-copy.any.js
index 6ae65119db687c..874478fdf11843 100644
--- a/encoding/textdecoder-copy.any.js
+++ b/encoding/textdecoder-copy.any.js
@@ -1,10 +1,21 @@
+function createViewWithBuffer(type, length) {
+  if (type === "ArrayBuffer") {
+    return new Uint8Array(new ArrayBuffer(length));
+  } else {
+    // See https://github.com/whatwg/html/issues/5380 for why not `new SharedArrayBuffer()`
+    // WebAssembly.Memory's size is in multiples of 64 KiB
+    const buffer = new WebAssembly.Memory({ shared:true, initial:1, maximum:1 }).buffer;
+    return new Uint8Array(buffer, 0, length);
+  }
+}
+
 ["ArrayBuffer", "SharedArrayBuffer"].forEach(arrayBufferOrSharedArrayBuffer => {
   test(() => {
-    const buf = new self[arrayBufferOrSharedArrayBuffer](2),
-          view = new Uint8Array(buf),
-          buf2 = new self[arrayBufferOrSharedArrayBuffer](2),
-          view2 = new Uint8Array(buf2),
-          decoder = new TextDecoder("utf-8");
+    const view = createViewWithBuffer(arrayBufferOrSharedArrayBuffer, 2);
+    const buf = view.buffer;
+    const view2 = createViewWithBuffer(arrayBufferOrSharedArrayBuffer, 2);
+    const buf2 = view2.buffer;
+    const decoder = new TextDecoder("utf-8");
     view[0] = 0xEF;
     view[1] = 0xBB;
     view2[0] = 0xBF;
diff --git a/encoding/textdecoder-streaming.any.js b/encoding/textdecoder-streaming.any.js
index e0c59472598fbd..0ec2a4908202b5 100644
--- a/encoding/textdecoder-streaming.any.js
+++ b/encoding/textdecoder-streaming.any.js
@@ -16,6 +16,17 @@ var octets = {
                  0xDF,0xFF]
 };
 
+function createViewWithBuffer(type, length) {
+  if (type === "ArrayBuffer") {
+    return new Uint8Array(new ArrayBuffer(length));
+  } else {
+    // See https://github.com/whatwg/html/issues/5380 for why not `new SharedArrayBuffer()`
+    // WebAssembly.Memory's size is in multiples of 64 KiB
+    const buffer = new WebAssembly.Memory({ shared:true, initial:1, maximum:1 }).buffer;
+    return new Uint8Array(buffer, 0, length);
+  }
+}
+
 ["ArrayBuffer", "SharedArrayBuffer"].forEach((arrayBufferOrSharedArrayBuffer) => {
     Object.keys(octets).forEach(function(encoding) {
         for (var len = 1; len <= 5; ++len) {
@@ -28,7 +39,7 @@ var octets = {
                     var sub = [];
                     for (var j = i; j < encoded.length && j < i + len; ++j)
                         sub.push(encoded[j]);
-                        var uintArray = new Uint8Array(new self[arrayBufferOrSharedArrayBuffer](sub.length));
+                        var uintArray = createViewWithBuffer(arrayBufferOrSharedArrayBuffer, sub.length);
                         uintArray.set(sub);
                     out += decoder.decode(uintArray, {stream: true});
                 }