[jumbo] Fix collision between test-alloc.cc and test-spaces.cc.

This fixes jumbo build by renaming Pseudorandom function after
https://chromium-review.googlesource.com/738204

Bug: chromium:777177
Change-Id: I86aa403928ad85ddd7dd779a8a43af9e34161928
Reviewed-on: https://chromium-review.googlesource.com/737637Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48974}

test/cctest/heap/test-spaces.cc

@@ -169,8 +169,7 @@ TEST(Regress3540) {
   delete memory_allocator;
 }
 
-
-static unsigned int Pseudorandom() {
+static unsigned int PseudorandomAreaSize() {
   static uint32_t lo = 2345;
   lo = 18273 * (lo & 0xFFFFF) + (lo >> 16);
   return lo & 0xFFFFF;
@@ -185,8 +184,8 @@ TEST(MemoryChunk) {
   size_t initial_commit_area_size, second_commit_area_size;
 
   for (int i = 0; i < 100; i++) {
-    initial_commit_area_size = Pseudorandom();
-    second_commit_area_size = Pseudorandom();
+    initial_commit_area_size = PseudorandomAreaSize();
+    second_commit_area_size = PseudorandomAreaSize();
 
     // With CodeRange.
     CodeRange* code_range = new CodeRange(isolate);