diff --git a/runtime/vm/flag_list.h b/runtime/vm/flag_list.h
index dc7f4b2..bbc7f05 100644
--- a/runtime/vm/flag_list.h
+++ b/runtime/vm/flag_list.h
@@ -25,7 +25,7 @@
   "Allow embedding absolute addresses in generated code.")                     \
 P(always_megamorphic_calls, bool, false,                                       \
   "Instance call always as megamorphic.")                                      \
-C(background_compilation, false, true, bool, true,                             \
+C(background_compilation, false, false, bool, false,                           \
   "Run optimizing compilation in background")                                  \
 R(break_at_isolate_spawn, false, bool, false,                                  \
   "Insert a one-time breakpoint at the entrypoint for all spawned isolates")   \
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 5ff3bb5..369bb28 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -37742,10 +37742,10 @@
     if ((blob_OR_source_OR_stream is Blob || blob_OR_source_OR_stream == null)) {
       return _blink.BlinkURL.instance.createObjectURL_Callback_1_(blob_OR_source_OR_stream);
     }
-    if ((blob_OR_source_OR_stream is MediaStream)) {
+    if ((blob_OR_source_OR_stream is MediaSource)) {
       return _blink.BlinkURL.instance.createObjectURL_Callback_1_(blob_OR_source_OR_stream);
     }
-    if ((blob_OR_source_OR_stream is MediaSource)) {
+    if ((blob_OR_source_OR_stream is MediaStream)) {
       return _blink.BlinkURL.instance.createObjectURL_Callback_1_(blob_OR_source_OR_stream);
     }
     throw new ArgumentError("Incorrect number or type of arguments");
diff --git a/sdk/lib/web_gl/dart2js/web_gl_dart2js.dart b/sdk/lib/web_gl/dart2js/web_gl_dart2js.dart
index 4a83a42..ac38baa 100644
--- a/sdk/lib/web_gl/dart2js/web_gl_dart2js.dart
+++ b/sdk/lib/web_gl/dart2js/web_gl_dart2js.dart
@@ -2771,7 +2771,7 @@
   @DomName('WebGLRenderingContext.texImage2D')
   @DocsEditable()
   void texImage2D(int target, int level, int internalformat, int format_OR_width, int height_OR_type, border_OR_canvas_OR_image_OR_pixels_OR_video, [int format, int type, TypedData pixels]) {
-    if (pixels != null && type != null && format != null && (border_OR_canvas_OR_image_OR_pixels_OR_video is int)) {
+    if (type != null && format != null && (border_OR_canvas_OR_image_OR_pixels_OR_video is int)) {
       _texImage2D_1(target, level, internalformat, format_OR_width, height_OR_type, border_OR_canvas_OR_image_OR_pixels_OR_video, format, type, pixels);
       return;
     }
@@ -2826,7 +2826,7 @@
   @DomName('WebGLRenderingContext.texSubImage2D')
   @DocsEditable()
   void texSubImage2D(int target, int level, int xoffset, int yoffset, int format_OR_width, int height_OR_type, canvas_OR_format_OR_image_OR_pixels_OR_video, [int type, TypedData pixels]) {
-    if (pixels != null && type != null && (canvas_OR_format_OR_image_OR_pixels_OR_video is int)) {
+    if (type != null && (canvas_OR_format_OR_image_OR_pixels_OR_video is int)) {
       _texSubImage2D_1(target, level, xoffset, yoffset, format_OR_width, height_OR_type, canvas_OR_format_OR_image_OR_pixels_OR_video, type, pixels);
       return;
     }
@@ -4894,7 +4894,7 @@
   @DocsEditable()
   @Experimental() // untriaged
   void texSubImage3D(int target, int level, int xoffset, int yoffset, int zoffset, int format_OR_width, int height_OR_type, canvas_OR_data_OR_depth_OR_image_OR_video, [int format, int type, TypedData pixels]) {
-    if (pixels != null && type != null && format != null && (canvas_OR_data_OR_depth_OR_image_OR_video is int)) {
+    if (type != null && format != null && (canvas_OR_data_OR_depth_OR_image_OR_video is int)) {
       _texSubImage3D_1(target, level, xoffset, yoffset, zoffset, format_OR_width, height_OR_type, canvas_OR_data_OR_depth_OR_image_OR_video, format, type, pixels);
       return;
     }
@@ -5600,7 +5600,7 @@
   @DocsEditable()
   @Experimental() // untriaged
   void texImage2D(int target, int level, int internalformat, int format_OR_width, int height_OR_type, border_OR_canvas_OR_image_OR_pixels_OR_video, [int format, int type, TypedData pixels]) {
-    if (pixels != null && type != null && format != null && (border_OR_canvas_OR_image_OR_pixels_OR_video is int)) {
+    if (type != null && format != null && (border_OR_canvas_OR_image_OR_pixels_OR_video is int)) {
       _texImage2D_1(target, level, internalformat, format_OR_width, height_OR_type, border_OR_canvas_OR_image_OR_pixels_OR_video, format, type, pixels);
       return;
     }
@@ -5663,7 +5663,7 @@
   @DocsEditable()
   @Experimental() // untriaged
   void texSubImage2D(int target, int level, int xoffset, int yoffset, int format_OR_width, int height_OR_type, canvas_OR_format_OR_image_OR_pixels_OR_video, [int type, TypedData pixels]) {
-    if (pixels != null && type != null && (canvas_OR_format_OR_image_OR_pixels_OR_video is int)) {
+    if (type != null && (canvas_OR_format_OR_image_OR_pixels_OR_video is int)) {
       _texSubImage2D_1(target, level, xoffset, yoffset, format_OR_width, height_OR_type, canvas_OR_format_OR_image_OR_pixels_OR_video, type, pixels);
       return;
     }
diff --git a/tools/VERSION b/tools/VERSION
index 0e28d7b..58909c0 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -28,4 +28,4 @@
 MINOR 16
 PATCH 0
 PRERELEASE 5
-PRERELEASE_PATCH 1
+PRERELEASE_PATCH 2
diff --git a/tools/dom/scripts/htmldartgenerator.py b/tools/dom/scripts/htmldartgenerator.py
index 89e3c3a..007f3f5 100644
--- a/tools/dom/scripts/htmldartgenerator.py
+++ b/tools/dom/scripts/htmldartgenerator.py
@@ -420,7 +420,7 @@
           else:
             checks.append('(%s is %s)' % (
                 parameter_name, test_type))
-        elif i >= number_of_required_in_dart:
+        elif i >= number_of_required_in_dart and not argument.type.nullable:
           checks.append('%s != null' % parameter_name)
 
       # There can be multiple presence checks.  We need them all since a later