IDL: Put [Exposed=Window] where it's not in Blink's renderer/modules/sensor

Though Web IDL spec removed [PrimaryGlobal] and made [Exposed] required [1],
many blink's IDL files have not followed it yet. So, this CL adds the keyword
to the IDL files which don't have the keyword yet in the renderer/module/sensor
directory.

[1] https://github.com/heycam/webidl/issues/365

Bug: 963267
Change-Id: I7f5dc89c160d8e369b9ac2609aee506315263305
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1672075Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#671948}

third_party/blink/renderer/modules/sensor/magnetometer.idl

@@ -6,6 +6,7 @@
 // https://w3c.github.io/magnetometer/#magnetometer-interface
 
 [
+    Exposed=Window,
     RuntimeEnabled=SensorExtraClasses,
     Constructor(optional SpatialSensorOptions sensorOptions),
     ConstructorCallWith=ExecutionContext,