Merge to XFA: Pass IJS_Runtime, not IJS_Context, to native object constructors.

Original Review URL: https://codereview.chromium.org/1389163007 .
(cherry picked from commit 848a13b6777cbff8cc4aea3ab3d69eaa0b82ae6c)

Merge conflics in:
fpdfsdk/src/javascript/JS_Runtime.cpp
fpdfsdk/src/javascript/JS_Runtime_Stub.cpp
fpdfsdk/src/jsapi/fxjs_v8.cpp

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1394993006 .
diff --git a/fpdfsdk/src/javascript/JS_EventHandler.cpp b/fpdfsdk/src/javascript/JS_EventHandler.cpp
index dd5c442..cb86fde 100644
--- a/fpdfsdk/src/javascript/JS_EventHandler.cpp
+++ b/fpdfsdk/src/javascript/JS_EventHandler.cpp
@@ -613,11 +613,11 @@
 Field* CJS_EventHandler::Source() {
   CJS_Runtime* pRuntime = m_pJSContext->GetJSRuntime();
   v8::Local<v8::Object> pDocObj = FXJS_NewFxDynamicObj(
-      pRuntime->GetIsolate(), m_pJSContext, CJS_Document::g_nObjDefnID);
+      pRuntime->GetIsolate(), pRuntime, CJS_Document::g_nObjDefnID);
   ASSERT(!pDocObj.IsEmpty());
 
   v8::Local<v8::Object> pFieldObj = FXJS_NewFxDynamicObj(
-      pRuntime->GetIsolate(), m_pJSContext, CJS_Field::g_nObjDefnID);
+      pRuntime->GetIsolate(), pRuntime, CJS_Field::g_nObjDefnID);
   ASSERT(!pFieldObj.IsEmpty());
 
   CJS_Document* pJSDocument =
@@ -636,11 +636,11 @@
 Field* CJS_EventHandler::Target_Field() {
   CJS_Runtime* pRuntime = m_pJSContext->GetJSRuntime();
   v8::Local<v8::Object> pDocObj = FXJS_NewFxDynamicObj(
-      pRuntime->GetIsolate(), m_pJSContext, CJS_Document::g_nObjDefnID);
+      pRuntime->GetIsolate(), pRuntime, CJS_Document::g_nObjDefnID);
   ASSERT(!pDocObj.IsEmpty());
 
   v8::Local<v8::Object> pFieldObj = FXJS_NewFxDynamicObj(
-      pRuntime->GetIsolate(), m_pJSContext, CJS_Field::g_nObjDefnID);
+      pRuntime->GetIsolate(), pRuntime, CJS_Field::g_nObjDefnID);
   ASSERT(!pFieldObj.IsEmpty());
 
   CJS_Document* pJSDocument =