Fix canvas state getting out of sync from smasks. (bug 1755507)

When ending an smask from restore, we first called restore on the
context which would update the current context and the suspended
context. However, we then called checkSMaskState which copies
the current context state to the suspended context. This caused
us to overwrite the restored values. Instead, restore the context
after we end the smask.

Fixes #11328 and bug 1755507

Author: brendandahl

src/display/canvas.js

@@ -1602,8 +1602,8 @@ class CanvasGraphics {
 
     if (this.stateStack.length !== 0) {
       this.current = this.stateStack.pop();
-      this.ctx.restore();
       this.checkSMaskState();
+      this.ctx.restore();
 
       // Ensure that the clipping path is reset (fixes issue6413.pdf).
       this.pendingClip = null;

test/pdfs/.gitignore

@@ -67,6 +67,7 @@
 !issue7901.pdf
 !issue8061.pdf
 !bug1721218_reduced.pdf
+!bug1755507_page1_reduced.pdf
 !issue8088.pdf
 !issue8125.pdf
 !issue8229.pdf

test/pdfs/bug1755507_page1_reduced.pdf

@@ -3685,6 +3685,12 @@
       "rounds": 1,
       "type": "eq"
     },
+    {  "id": "bug1755507_page1_reduced",
+       "file": "pdfs/bug1755507_page1_reduced.pdf",
+       "md5": "319d73b8fd680cdc583d69b7f7ab29e9",
+       "rounds": 1,
+       "type": "eq"
+    },
     {  "id": "issue4244",
        "file": "pdfs/issue4244.pdf",
        "md5": "26845274a32a537182ced1fd693a38b2",