Revert "Remove deferred proxy machinery"

This reverts commit a3987cc5873c9bce758fa3843bb801c95d282bbd.

Reason for revert: Keeping it

Original change's description:
> Remove deferred proxy machinery
>
> These aren't used any more in favor of lazy proxies.
>
> Bug: skia:11288
> Change-Id: I992e1a3dd343e0ebc7f3a4f18c0054453dfebbaf
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/366896
> Commit-Queue: Adlai Holler <adlai@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>

TBR=bsalomon@google.com,robertphillips@google.com,adlai@google.com

Bug: skia:11288
Change-Id: Iafa9ed18a772e451349dfad61ee462df963028be
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368376
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Adlai Holler <adlai@google.com>
diff --git a/src/gpu/GrResourceAllocator.cpp b/src/gpu/GrResourceAllocator.cpp
index d7e6851..2a1d44d 100644
--- a/src/gpu/GrResourceAllocator.cpp
+++ b/src/gpu/GrResourceAllocator.cpp
@@ -94,7 +94,12 @@
     if (Interval* intvl = fIntvlHash.find(proxy->uniqueID().asUInt())) {
         // Revise the interval for an existing use
 #ifdef SK_DEBUG
-        if (isDirectDstRead) {
+        if (0 == start && 0 == end) {
+            // This interval is for the initial upload to a deferred proxy. Due to the vagaries
+            // of how deferred proxies are collected they can appear as uploads multiple times
+            // in a single opsTasks' list and as uploads in several opsTasks.
+            SkASSERT(0 == intvl->start());
+        } else if (isDirectDstRead) {
             // Direct reads from the render target itself should occur w/in the existing
             // interval
             SkASSERT(intvl->start() <= start && intvl->end() >= end);