Fix type confusion in libpac

From the upstream patch
(https://chromium.googlesource.com/v8/v8/+/e33fd30777f99a0d6e16b16d096a2663b1031457%5E%21/#F0):

"""
Fix HAliasAnalyzer for constants
"""

Bug: 117606285

Test: /data/local/nativetest/proxy_resolver_v8_unittest/proxy_resolver_v8_unittest

Test: gts-tradefed run gts --test \
  com.google.android.gts.devicepolicy.DeviceOwnerTest#testProxyPacProxyTest \
  --module GtsGmscoreHostTestCases

Test: PoC from bug report

Merged-In: I2e02d994f107e64e4f465b4d8a02d4159a95240e
Change-Id: I297f27c69e94666c9f61efb216244b3d534cd018
(cherry picked from commit cad793346e55ab582a4aa43a246bb3cb10b76109)
diff --git a/src/crankshaft/hydrogen-alias-analysis.h b/src/crankshaft/hydrogen-alias-analysis.h
index 1f32b7ac..d06aabc 100644
--- a/src/crankshaft/hydrogen-alias-analysis.h
+++ b/src/crankshaft/hydrogen-alias-analysis.h
@@ -43,7 +43,7 @@
     }
 
     // Constant objects can be distinguished statically.
-    if (a->IsConstant()) {
+    if (a->IsConstant() && b->IsConstant()) {
       return a->Equals(b) ? kMustAlias : kNoAlias;
     }
     return kMayAlias;