Auto merge of #23696 - servo:hl, r=jdm

Add UWP port - bis

This is #23658 with some fixes:
- removed nspr from DLL dependencies (was breaking VS build)
- exclude symbols from header file (was breaking VS build)
- rebased

Before merging:
- please check the rebased commit that introduces the `--uwp` option (things moved around since 7c85dc09b5)
- should we wait until the WR fix lands upstream?

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python/servo/build_commands.py

@@ -30,7 +30,7 @@ from mach.decorators import (
 from mach.registrar import Registrar
 
 from mach_bootstrap import _get_exec_path
-from servo.command_base import CommandBase, cd, call, check_call, BIN_SUFFIX
+from servo.command_base import CommandBase, cd, call, check_call, BIN_SUFFIX, append_to_path_env
 from servo.util import host_triple
 
 
@@ -169,7 +169,7 @@ class MachCommands(CommandBase):
     @CommandBase.build_like_command_arguments
     def build(self, release=False, dev=False, jobs=None, params=None,
               no_package=False, verbose=False, very_verbose=False,
-              target=None, android=False, magicleap=False, libsimpleservo=False,
+              target=None, android=False, magicleap=False, libsimpleservo=False, uwp=False,
               features=None, **kwargs):
         opts = params or []
         features = features or []
@@ -240,6 +240,21 @@ class MachCommands(CommandBase):
                 env['CXXFLAGS'] = ''
             env["CXXFLAGS"] += "-mmacosx-version-min=10.10"
 
+        if uwp:
+            # Don't try and build a desktop port.
+            libsimpleservo = True
+
+            # Ensure that the NuGet ANGLE package containing libEGL is accessible
+            # to the Rust linker.
+            append_to_path_env(
+                path.join(
+                    os.getcwd(), "support", "hololens", "packages",
+                    "ANGLE.WindowsStore.2.1.13", "bin", "UAP", "x64"
+                ),
+                env,
+                "LIB"
+            )
+
         if android:
             if "ANDROID_NDK" not in env:
                 print("Please set the ANDROID_NDK environment variable.")
@@ -532,7 +547,7 @@ class MachCommands(CommandBase):
 
         status = self.run_cargo_build_like_command(
             "build", opts, env=env, verbose=verbose,
-            target=target, android=android, magicleap=magicleap, libsimpleservo=libsimpleservo,
+            target=target, android=android, magicleap=magicleap, libsimpleservo=libsimpleservo, uwp=uwp,
             features=features, **kwargs
         )
 
@@ -584,7 +599,8 @@ class MachCommands(CommandBase):
                     for lib in libs:
                         print("WARNING: could not find " + lib)
 
-                package_generated_shared_libraries(["libEGL.dll"], build_path, servo_exe_dir)
+                if not uwp:
+                    package_generated_shared_libraries(["libEGL.dll"], build_path, servo_exe_dir)
 
                 # copy needed gstreamer DLLs in to servo.exe dir
                 target_triple = target or host_triple()

python/servo/command_base.py

@@ -782,6 +782,11 @@ install them, let us know by filing a bug!")
                 action='store_true',
                 help='Build with frame pointer enabled, used by the background hang monitor.',
             ),
+            CommandArgument(
+                '--uwp',
+                default=None,
+                action='store_true',
+                help='Build for HoloLens (x64)'),
             CommandArgument('--with-raqote', default=None, action='store_true'),
             CommandArgument('--without-wgl', default=None, action='store_true'),
         ]
@@ -809,6 +814,7 @@ install them, let us know by filing a bug!")
         target=None, android=False, magicleap=False, libsimpleservo=False,
         features=None, debug_mozjs=False, with_debug_assertions=False,
         with_frame_pointer=False, with_raqote=False, without_wgl=False,
+        uwp=False,
     ):
         env = env or self.build_env()
         target, android = self.pick_target_triple(target, android, magicleap)
@@ -836,6 +842,12 @@ install them, let us know by filing a bug!")
             features.append("debugmozjs")
         if not magicleap:
             features.append("native-bluetooth")
+        if uwp:
+            features.append("canvas2d-raqote")
+            features.append("no_wgl")
+        else:
+            # Non-UWP builds provide their own libEGL via mozangle.
+            features.append("egl")
         if with_raqote and "canvas2d-azure" not in features:
             features.append("canvas2d-raqote")
         elif "canvas2d-raqote" not in features: